CN103873054A - Clock generator - Google Patents
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- CN103873054A CN103873054A CN201410126174.2A CN201410126174A CN103873054A CN 103873054 A CN103873054 A CN 103873054A CN 201410126174 A CN201410126174 A CN 201410126174A CN 103873054 A CN103873054 A CN 103873054A
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Abstract
The invention provides a clock generator which comprises an internally-arranged oscillator circuit and a phase locked loop circuit coupled with the internally-arranged oscillator circuit. The phase locked loop circuit and the internally-arranged oscillator circuit share an oscillator circuit and a filter circuit. Under the control of enable signals, output signals of the clock generator are output signals of the internally-arranged oscillator circuit or output signals of the phase locked loop circuit. The clock generator can provide proper clock signals in a targeted mode according to different requirements of application so as to achieve the optimization of performance and cost.
Description
Technical field
The present invention relates to clock generator, relate in particular to a kind of two-in-one clock generator.
Background technology
Making rapid progress of science and technology, makes developing trend low-power consumption, small size and the low cost of various device, and clock generating circuit also trends towards integrated on full sheet, high accuracy, high-frequency accurately.In prior art, generally provide the circuit of clock signal to have to various circuit chips following several:
A kind of is clock generation circuit based on ring oscillator.Use based on the clock generation circuit of ring oscillator comparatively extensive, but in CMOS technique, owing to there is the problem such as unsteadiness of temperature, technique and supply voltage, the output frequency stability that makes to be integrated in the clock circuit in sheet is poor.
Another is lax (Relaxation) oscillator of RC, and because its frequency accuracy is higher, current development is comparatively rapid, and still, the operating frequency of RC relaxation oscillator is conventionally lower, is not suitable for the clock signal application of upper frequency.
As shown in Figure 1, it uses benchmark crystal oscillator 102 to produce signal by crystal-oscillator circuit 101 to the third circuit structure, and obtains clock signal by phase-locked loop (PLL)/delay locked loop (DLL) 100 lockings.Wherein, the structure of phase-locked loop as shown in Figure 3, mainly comprises frequency and phase discrimination circuit 12, charge pump circuit 13, ring oscillator 14, divider circuit 16, and the output signal of crystal oscillator obtains stable clock output via crystal-oscillator circuit 10 and this phase-locked loop.
The 4th kind is built-in pierce circuit, its circuit structure as shown in Figure 2, mainly comprise that basic current produces circuit 11, current comparator 17, ring oscillator 13, non-overlapped signal generating circuit 14, frequency-electric current conversion circuit 15, this built-in pierce circuit can be realized the stable output of clock signal in certain accuracy rating.
For consumer electronics product, what generally adopt for generation of the pierce circuit of clock reference is all the third structure at present.Still with reference to figure 1, crystal oscillator 102 produces signal by crystal-oscillator circuit 101, and lock to obtain clock signal by PLL/DLL1100, need to obtain suitable clock signal with phase-locked loop (PLL) or delay locked loop (DLL) at chip internal (being on sheet).Pierce circuit shown in Fig. 1 can be realized very high precision, is generally 1～100ppm.But the scheme shown in Fig. 1 needs the extra external crystal-controlled oscillation 102 increasing, and has not only greatly improved the cost of product, and need to take larger chip area and power consumption, and reduced the competitiveness of whole chip.Some to the application in the consumer product of cost compare sensitivity in, the products such as such as toy remote control product, controlled in wireless product and infrared remote control, in the situation that guaranteeing clock signal output accuracy, also need the clock signal generating circuit of a relatively low cost.
Summary of the invention
The technical problem to be solved in the present invention is to provide a kind of clock generator, can require to provide targetedly suitable clock signal for the difference of application, to arrive the optimization of performance and cost.
For solving the problems of the technologies described above, the invention provides a kind of clock generator, comprising:
Built-in oscillating circuit;
With the phase-locked loop circuit of described built-in oscillating circuit coupling, this phase-locked loop circuit and described built-in oscillating circuit shared oscillator circuit and filter circuit;
Wherein, under the control of enable signal, the output signal that the output signal of described clock generator is this built-in oscillating circuit or the output signal of this phase-locked loop circuit.
According to one embodiment of present invention, described built-in oscillating circuit comprises:
Basic current produces circuit, for generation of reference current;
Current comparator, its first input end is connected with the output that described basic current produces circuit;
Described filter circuit, its input connects the output of described current comparator, and this filter circuit carries out filtering to the comparison signal of described current comparator output and controls voltage to produce;
Described pierce circuit, its input connects the output of described filter circuit, and this pierce circuit produces output signal under the control of described control voltage;
Non-overlapped signal generating circuit, its input connects the output of described pierce circuit, and this non-overlapped signal generating circuit produces non-overlapped at least two-way clock signal according to the output signal of described pierce circuit;
Frequency-electric current conversion circuit, its input connects the output of described non-overlapped signal generating circuit, its output connects the second input of described current comparator, the at least two-way clock signal that this frequency-electric current conversion circuit produces described non-overlapped signal generating circuit is converted into feedback current, and this current comparator compares the reference current of this feedback current and the generation of described basic current generation circuit.
According to one embodiment of present invention, described built-in oscillating circuit also comprises: divider circuit, the output of described pierce circuit connects the input of described non-overlapped signal generating circuit via described divider circuit, this frequency divider carries out frequency division to the output signal of described pierce circuit.
According to one embodiment of present invention, described basic current produces circuit and comprises:
The first operational amplifier, its first input end receives the first default reference voltage;
The first amplifier tube, its control end connects the output of described the first operational amplifier, and its first end connects power supply, and its second end connects the second input of described the first operational amplifier;
Trimming resistors, the second end of described the first amplifier tube is via described trimming resistors ground connection;
Mirror image circuit, does mirror image to the electric current of described the first amplifier tube of flowing through, and the output of this mirror image circuit produces the output of circuit as described basic current.
According to one embodiment of present invention, described trimming resistors comprises positive temperature coefficient resistor and the negative temperature coefficient resister of series connection.
According to one embodiment of present invention, described mirror image circuit comprises one or more mirror image pipes, the control end of these one or more mirror image pipes connects the control end of described the first amplifier tube, the first end of these one or more mirror image pipes connects the first end of described the first amplifier tube, and the second end of these one or more mirror image pipes is as the output of described mirror image circuit.
According to one embodiment of present invention, described frequency-electric current conversion circuit comprises:
The second operational amplifier, its first input end receives the second default reference voltage;
The second amplifier tube, its control end connects the output of described the second operational amplifier, and its second end connects the second input of described the second operational amplifier;
The first switch, its first end connects the second end of described the second amplifier tube, and its control end receives the first clock signal of described non-overlapped signal generating circuit output;
Charge and discharge capacitance, its first end connects the second end of described the first switch, its second end ground connection;
Second switch, its first end connects the first end of described charge and discharge capacitance, its second end ground connection;
Electric current output module, connects the first end of described the second amplifier tube, and the first end of described the second amplifier tube is via this electric current output module output feedback current.
According to one embodiment of present invention, described frequency-electric current conversion circuit also comprises: filter capacitor, its first end connects the second end of described the second operational amplifier, its second end ground connection.
According to one embodiment of present invention, described electric current output module comprises:
The first efferent duct, its first end connects power supply, and its control end connects the first end of described the second amplifier tube;
The second efferent duct, its first end connects the second end of described the first efferent duct, and its second end connects the first end of described the second amplifier tube.
According to one embodiment of present invention, described current comparator comprises:
First mirror image tube, its first end connects power supply, and its control end connects the control end of described the first efferent duct;
The second mirror image pipe, its first end connects the second end of described first mirror image tube, and its control end connects the control end of described first mirror image tube, and its second end is as the output of described current comparator;
Limit electric capacity, its first end connects power supply, and its second end connects the second end of described the second mirror image pipe;
Mirror image module, its first mirror connects the second end of described the second mirror image pipe as input, and its second mirror image input receives described basic current and produces the reference current that circuit produces.
According to one embodiment of present invention, this clock generator also comprises: voltage stabilizing generator, and for described the second reference voltage is provided.
According to one embodiment of present invention, the frequency of the output signal of described pierce circuit is affected by environment, when temperature rise, this control voltage instantaneous does not change, the frequency of the output signal of described pierce circuit declines, the frequency of at least two-way clock signal of described non-overlapped signal generating circuit output declines, the feedback current of this frequency-electric current conversion circuit output starts to reduce, and described reference current remains unchanged, so the comparison signal amplitude of this current comparator output declines, the corresponding decline of described control voltage, the frequency of the output signal of described pierce circuit increases with the decline of described control voltage, the feedback current of described frequency-electric current conversion circuit output increases thereupon, thus, negative feedback regulates and continues to carry out, until described feedback current and reference current are equal, till the loop of described built-in oscillating circuit is stablized again.
According to one embodiment of present invention, described phase-locked loop circuit comprises:
Frequency and phase discrimination circuit, its first input end receives reference frequency signal, the output signal of this reference frequency signal and described pierce circuit is compared and produce output signal, and the output signal of this frequency and phase discrimination circuit is proportional to the phase difference of the output signal of described reference frequency signal and described pierce circuit;
Charge pump circuit, its input connects the output of described frequency and phase discrimination circuit, and this charge pump circuit is according to the output signal generation current signal of described frequency and phase discrimination circuit;
Described filter circuit, its input connects the output of described charge pump circuit, and described filter circuit filtering produces control signal;
Described pierce circuit, its input connects the output of described filter circuit, and its output connects the second input of described frequency and phase discrimination circuit, and this pierce circuit produces output signal under the control of described control voltage.
According to one embodiment of present invention, described phase-locked loop circuit also comprises: divider circuit, the output of described pierce circuit connects the second input of described frequency and phase discrimination circuit via described divider circuit.
According to one embodiment of present invention, the output signal frequency of described pierce circuit is affected by environment, when temperature rise, described control voltage instantaneous does not change, the frequency of the output signal of described pierce circuit declines, the current signal of described charge pump circuit is subject to the adjusting of described frequency and phase discrimination circuit, in the time that the frequency of this reference frequency signal of frequency ratio of the output signal of described pierce circuit is large, the current signal of this charge pump circuit flows out described filter circuit, this control voltage drop, the frequency of the output signal of this pierce circuit increases; When the frequency hour of this reference frequency signal of frequency ratio of the output signal of described pierce circuit, the current signal of this charge pump circuit flows into this filter circuit, and this control voltage rises, and the frequency of the output signal of this pierce circuit reduces; Above-mentioned comparison procedure continues to carry out, until the frequency of the output signal of this pierce circuit is identical with the frequency of this reference frequency signal.
According to one embodiment of present invention, described filter circuit comprises:
The first electric capacity, its first end connects the input of described filter circuit, its second end ground connection;
The first resistance, its first end connects the input of described filter circuit;
The second electric capacity, its first end connects the second end of described the first resistance, its second end ground connection;
The 3rd switch, its first end connects the first end of described the first resistance, its second end connects the second end of described the first resistance, its control end receives the control signal being associated with described enable signal, when the output signal of described clock generator is the output signal of this built-in oscillating circuit, the 3rd switch closure described in described control signal control, when output signal that the output signal of described clock generator is this phase-locked loop circuit, the 3rd switch disconnects described in described control signal control.
According to one embodiment of present invention, described pierce circuit is ring oscillator, comprise multiple voltage controlled oscillators, the input of described multiple voltage controlled oscillators and the output formation ring-type of connecting successively, the control end of described multiple voltage controlled oscillators links together as the input of described pierce circuit.
According to one embodiment of present invention, described built-in oscillating circuit and phase-locked loop circuit are integrated in same chip.
According to one embodiment of present invention, when described enable signal is logic low, the output signal that the output signal of described clock generator is this built-in oscillating circuit; In the time that described enable signal is logic high, the output signal that the output signal of described clock-signal generator is described phase-locked loop circuit.
According to one embodiment of present invention, the frequency range of the output signal of described clock generator is set to 27MHZ～49MHZ, for remote-control toy; Or the frequency range of the output signal of described clock generator is set to 315MHZ～433MHZ, for wireless control apparatus; Or the frequency range of the output signal of described clock generator is set to 1MHZ～10MHZ, for infrared remote control equipment or MEMS equipment.
Compared with prior art, the present invention has the following advantages:
In the clock generator of the embodiment of the present invention, be integrated with built-in oscillating circuit and phase-locked loop circuit, the two shares same pierce circuit and filter circuit, wherein, built-in oscillating circuit can be even all integrated in chip, without volume, external crystal-controlled oscillation is additionally set, saved process costs, and built-in oscillating circuit has higher stability in the situation such as temperature deviation and power supply drift, clock signal that can stable output; And phase-locked loop circuit can produce the high clock signal of precision, therefore, the clock generator of the present embodiment has the advantage of built-in oscillating circuit and phase-locked loop circuit concurrently, can meet the requirement of different application field, different system, and share and reduced area occupied by parts between two kinds of circuit, save cost.
Accompanying drawing explanation
Fig. 1 is the structural representation of a kind of clock signal generating circuit that utilizes crystal oscillator in prior art;
Fig. 2 is the structural representation of a kind of built-in pierce circuit in prior art;
Fig. 3 is the structural representation of a kind of phase-locked loop circuit in prior art;
Fig. 4 is the structural representation of the clock generator of first embodiment of the invention;
Fig. 5 is the detailed circuit diagram that in Fig. 4, basic current produces circuit;
Fig. 6 is the detailed circuit diagram of Fig. 4 medium frequency-electric current conversion circuit and current comparator;
Fig. 7 is the detailed circuit diagram of the pierce circuit in Fig. 4;
Fig. 8 is the structural representation of the clock generator of figure second embodiment of the invention.
Embodiment
Below in conjunction with specific embodiments and the drawings, the invention will be further described, but should not limit the scope of the invention with this.
The first embodiment
With reference to figure 4, the clock generator of the first embodiment mainly comprises built-in oscillator and phase-locked loop circuit, wherein, built-in oscillator can comprise: basic current produces circuit 41, current comparator 42, filter circuit 21, pierce circuit 43, non-overlapped signal generating circuit 44 and frequency-electric current conversion circuit 45; Phase-locked loop circuit can comprise: frequency and phase discrimination circuit 49, charge pump circuit 48, filter circuit 21 and pierce circuit 43.
The frequency range of the clock generator of the present embodiment can be set to 27MHZ～49MHZ, for the equipment of remote-control toy and so on; Or its frequency range also can be set to 315MHz～433MHZ, for wireless control apparatus; Or its frequency range also can be set to 1MHZ-10MHZ, then after frequency division for infrared remote control equipment and the needed band limits of MEMS equipment of 38KHz.
In the first embodiment, built-in oscillator and phase-locked loop circuit share same pierce circuit 43 and filter circuit 21, to reduce chip area.The output signal fout of clock generator, under the control of enable signal En, switches between the output signal of built-in oscillating circuit and the output signal of phase-locked loop circuit.For example, enable signal En can be used as the enable signal of the one or more modules in built-in oscillating circuit and phase-locked loop circuit, and with the work of controlling corresponding module whether, thereby the work of controlling built-in oscillator and phase-locked loop circuit whether.
As a nonrestrictive example, enable signal En can, via the enable signal En_buf after being cushioned after inverter 50 and inverter 51 bufferings, control and switch built-in oscillator and phase-locked loop circuit with the enable signal En_buf after buffering afterwards.For example, in the time that enable signal En is logic high, the enable signal En_buf after buffering is also logic high, and this clock generator is configured to phase-locked loop circuit, namely built-in oscillating circuit is not worked, the output signal that the output signal of this clock generator is phase-locked loop circuit; In the time that enable signal En is logic low, enable signal En_buf after buffering is also logic low, this clock generator is configured to built-in oscillating circuit, and namely phase-locked loop circuit is not worked, the output signal that the output signal of this clock generator is built-in oscillating circuit.
As a preferred embodiment, this built-in oscillating circuit and phase-locked loop circuit can be integrated on same chip, and namely whole clock generator is clock generator on sheet.Wherein, built-in oscillating circuit adopts the form of negative feedback closed loop, utilize frequency-electric current transform mode to realize clock generation function, make the built-in oscillating circuit can be all integrated in chip, without outside, crystal oscillator is additionally set, can save process costs, and be converted into direct current by the frequency of oscillation that pierce circuit 43 is produced, and compare with the current Ib that basic current generation circuit 41 produces, then comparative result is fed back to the control input end of pierce circuit 43, to change the frequency of pierce circuit 43, thereby compensate by the deviation to frequency signal, make the operating frequency of loop stability output Low Drift Temperature, produce the frequency signal of certain precision.This built-in oscillating circuit not only has higher stability in the situation that of technique, temperature deviation and supply voltage deviation, can export a stable clock signal, and its frequency signal scope is wide, goes for various application occasions.And in, the exigent system of clock accuracy less demanding to cost control at some, can utilize phase-locked loop circuit to produce the high clock signal of precision, to meet the requirement of different clients and system.
Below the course of work of modules and this clock generator is described in detail.
Basic current produces circuit 41 for generation of reference current Ib.Fig. 5 shows a limiting examples of basic current generation circuit 41, comprising: the first operational amplifier A 1, and its first input end receives the first default reference voltage Vref; The first amplifier tube M1, its control end connects the output of the first operational amplifier A 1, its first end connects power vd DA, its second end connects the second input of the first operational amplifier A 1, this first amplifier tube M1 can be for example MOS transistor, its control end is the grid of MOS transistor, and its first end and the second end are respectively source electrode and the drain electrode of MOS transistor; Trimming resistors Rp+Rn, the second end of this first amplifier tube M1 is via trimming resistors Rp+Rn ground connection; Mirror image circuit, electric current to the first amplifier tube M1 that flows through does mirror image, the output of this mirror image circuit produces the output of circuit as basic current, this mirror image circuit can comprise one or more mirror image pipe Mp1, the control end of these one or more mirror image pipe Mp1 connects the control end of the first amplifier tube M1, the first end of these one or more mirror image pipe Mp1 connects the first end of the first amplifier tube M1, and the second end of these one or more mirror image pipe Mp1 is as the output of mirror image circuit.
As a preferred embodiment, in the example shown in Fig. 5, trimming resistors Rp+Rn comprises positive temperature coefficient resistor and the negative temperature coefficient resister of series connection; This mirror image circuit comprises a mirror image pipe Mp1, and its control end connects the control end of the first amplifier tube M1, and its first end connects the first end of the first amplifier tube M1, and its second end is as the output of mirror image circuit, for output reference current Ib.Wherein, mirror image pipe Mp1 can be MOS transistor, but is not limited to this.
In addition, mirror image circuit can also comprise the mirror image circuit structure of cascade, thereby further reduces the temperature coefficient of image current, makes the electric current of output substantially temperature independent.
In addition, mirror image circuit can also comprise multiple mirror image pipe Mp1, adopts the overriding mirror image circuit of multichannel, thereby increases control bit, to increase the scope of output frequency coarse adjustment, meets the requirements of output frequency.
Moreover because the deviation of the resistance that process deviation brings, trimming resistors Rp+Rn also can be by the control of multidigit control bit, thereby increase the adjustable range of resistance, controls output frequency fine adjustment range, to meet the requirements of output frequency.
Still with reference to figure 4, non-overlapped clock signal clk 1 and the CLK2 of two-way that frequency-electric current conversion circuit 45 produces non-overlapped signal generating circuit 44 is converted into feedback current Iout; Current comparator 42 produces for feedback current Iout that frequency-electric current conversion circuit 45 is produced and basic current the reference current Ib that circuit 41 produces and compares.
With reference to figure 6, Fig. 6 shows a limiting examples of frequency-electric current conversion circuit and current comparator.Wherein, frequency-electric current conversion circuit comprises that 45 comprise: the second operational amplifier A 2, and its first input end receives the second default reference voltage Vb; The second amplifier tube M4, its control end connects the output of the second operational amplifier A 2, and its second end connects the second input of the second operational amplifier A 2; The first K switch 1, its first end connects the second end of the second amplifier tube M4, and its control end receives the first clock signal clk 1 of non-overlapped signal generating circuit output; Charge and discharge capacitance Cc, its first end connects the second end of the first K switch 1, its second end ground connection; Second switch K2, its first end connects the first end of charge and discharge capacitance Cc, its second end ground connection; Electric current output module, the first end of connection the second amplifier tube M4, the first end of the second amplifier tube M4 is via this electric current output module output feedback current Iout; Filter capacitor Cb, its first end connects the second end of the second operational amplifier A 2, its second end ground connection, this filter capacitor Cb can reduce the phase noise of built-in oscillating circuit.Wherein, the first K switch 1 and second switch K2 are used for controlling charge and discharge capacitance Cc and carry out charge or discharge, to form equivalent resistance module.
Wherein, as a nonrestrictive example, electric current output module can comprise: the first efferent duct M6, and its first end connects power vd DA, and its control end connects the first end of the second amplifier tube M4; The second efferent duct M5, its first end connects the second end of the first efferent duct M6, and its second end connects the first end of the second amplifier tube M4.The second amplifier tube M4, the first efferent duct M6 and the second efferent duct M5 can be MOS transistor, but are not limited to this.
As a nonrestrictive example, mirror image module can comprise the 9th MOS transistor M9, the tenth MOS transistor M10, the 11 MOS transistor to the 12 MOS transistor M12, the drain electrode of the 9th MOS transistor M9 connects the second end of the second mirror image pipe M8, the source electrode of the 9th MOS transistor M9 connects the drain electrode of the tenth MOS transistor M10, the grid of the 9th MOS transistor M9 connects the grid of the 11 MOS transistor M11, the source ground of the tenth MOS transistor M10, the grid of the tenth MOS transistor M10 connects the 12 grid of MOS transistor M12 and the source electrode of the 11 MOS transistor M11, the grounded drain of the 12 MOS transistor M12, the drain electrode of the 11 MOS transistor M11 receives reference current Ib.Wherein, limit capacitor C 10 makes the control voltage Vctr that current comparator 42 is exported produce a limit, thereby stablizes whole built-in oscillating circuit.
Still with reference to figure 4, filter circuit 21 carries out filtering to the output signal of current comparator 42, with controlled voltage Vctr.Can comprise: the first capacitor C 1, its first end connects the input of filter circuit, its second end ground connection; The first resistance R, its first end connects the input of filter circuit; The second capacitor C 2, its first end connects the second end of the first resistance R 1, its second end ground connection; The 3rd K switch 3, its first end connects the first end of the first resistance R 1, its second end connects the second end of the first resistance R 1, its control end (for example receives the control signal that is associated with enable signal En, this control signal can be the inversion signal K3_c of enable signal En after anti-phase), when the output signal fout of this clock generator is the output signal of this built-in oscillating circuit, these control signal control the 3rd K switch 3 closures, when the output signal fout of clock generator is the output signal of this phase-locked loop circuit, control signal control the 3rd K switch 3 disconnects.In other words, in the time that this clock generator is used as built-in oscillating circuit, the correlation module of phase-locked loop circuit turn-offs, the 3rd K switch 3 closures, and the active component that makes filter circuit 21 is the first capacitor C 1 and the second capacitor C 2; In the time that this clock generator is used as phase-locked loop circuit, the correlation module of built-in oscillating circuit turn-offs, the 3rd K switch 3 disconnects, and the active component that makes filter circuit 21 is the first capacitor C 1, the second capacitor C 2 and the first resistance R 1, and filter circuit 21 is equivalent to RC low pass filter.Adopt such filter circuit 21, filter circuit 21 its frequency response curve when for built-in oscillating circuit and phase-locked loop circuit has comparatively balanced poles and zeros assignment.
Certainly, it will be appreciated by those skilled in the art that the filter circuit 21 shown in Fig. 4 is only preferred example, this filter circuit 21 can also adopt other suitable structures, for example conventional low pass filter, it can have fixing structure when for built-in oscillating circuit and phase-locked loop circuit.
Still with reference to figure 4, this pierce circuit 43 produces output signal fout under the control of controlling voltage Vctr, and the frequency of the output signal fout that control voltage Vctr produces pierce circuit 43 is carried out feedback correction, until the frequency stabilization of this output signal fout.As a nonrestrictive example, this pierce circuit 43 can be ring oscillator, the output signal fout of this pierce circuit 43 is as the output signal of whole clock generator, in addition, another output signal fout1 of this pierce circuit 43 conventionally can be identical with output signal fout, but another output signal fout1 can be also the frequency signal being associated with output signal fout.This pierce circuit 43 can be for example ring oscillator, its structure as shown in Figure 7, this ring oscillator for example comprises multiple voltage controlled oscillator 71(, example shown in Fig. 7 comprises 4 voltage controlled oscillators 71), the input of multiple voltage controlled oscillators 71 and the output formation ring-type of connecting successively, the control end of multiple voltage controlled oscillators 71 links together as the control input end of whole ring oscillator, and this control input end receives controls voltage Vctr.The voltage Vctr frequency controlled processed of the output of ring oscillator controls, and for example, along with controlling reducing of voltage Vctr, the frequency of output signal increases.By the structure of selection ring oscillator and by suitable parameter designing, ring oscillator can be operated in identical frequency under different temperatures.For example, the delay unit in ring oscillator can adopt positive feedback technique to carry out the time of delay of control lag unit, thereby changes the frequency signal of circuit.
Furthermore, in conjunction with Fig. 4, Fig. 6 and Fig. 7, in the time of built-in oscillating circuit steady operation, its output frequency can be:
Wherein, the output frequency that fout is built-in oscillating circuit, Cc is the capacitance of charge and discharge capacitance Cc, (Rp+Rn) is the resistance value of trimming resistors Rp+Rn, and K is proportionality coefficient, and for definite circuit structure, K is constant.
Non-overlapped signal generating circuit 44 produces non-overlapped clock signal clk 1 and CLK2 according to the output signal fout1 of pierce circuit 43, and for example, this clock signal clk 1 and CLK2 can be with the out of phase two paths of signals of frequency.
Continue with reference to figure 4, the phase-locked loop circuit in this clock generator can comprise: frequency and phase discrimination circuit 49, and its first input end receives reference frequency signal fref; Charge pump circuit 48, its input connects the output of frequency and phase discrimination circuit 49; Filter circuit 21, its input connects the output of charge pump circuit 48; Pierce circuit 43, its input connects the output of filter circuit 21, and its output connects the second input of frequency and phase discrimination circuit 49.
Wherein, reference frequency signal fref can provide by crystal oscillator and crystal-oscillator circuit 20.Conventionally, crystal oscillator and crystal-oscillator circuit 20 can be arranged on outside sheet, are namely not integrated on same chip with clock generator.Frequency and phase discrimination circuit 49, charge pump circuit 48 can adopt any suitable structure in prior art, repeat no more here.
Described frequency and phase discrimination circuit 49 compares the output signal fout of input reference signal fref and pierce circuit 43, and output is for controlling the signal of charge pump circuit 48.Charge pump circuit 48 is the electric current in inflow direction or outflow direction according to the output signal output of frequency and phase discrimination circuit 49, filter circuit 21 receives the current signal from charge pump circuit 48, and remove the high-frequency noise being included in current signal, produce the control voltage Vctr for controlling pierce circuit 43.Control voltage Vctr control pierce circuit 43 and produce output signal fout1 and fout.Output signal fout1 and input reference signal fref compare again, and this comparison procedure is carried out repeatedly, until output signal fout1 and two signals of input reference signal fref equate.
In order to obtain the clock output signal of high accuracy, high stability, the output signal fout1 that phase-locked loop circuit produces pierce circuit 43 realizes and synchronizeing in phase place and frequency with input reference signal fref, this input reference signal can have low noise and high accuracy (being generally 1-100ppm), thereby the clock that phase-locked loop circuit produces is high accuracy, low noise output signal.In the course of work of phase-locked loop circuit, the output signal fout1 of pierce circuit 43 may be subject to the impact of the environment such as temperature, process deviation and supply voltage, for example, when assumed temperature rises, control voltage Vctr moment does not change, the frequency of the output signal fout of pierce circuit 43 declines, the electric current of the output signal control charge pump circuit 48 of frequency and phase discrimination circuit 49 so.In the time that the frequency of the frequency ratio input reference signal fref of output signal fout1 is large, the outflow of bus current filter circuit 21 of charge pump circuit 48, controls voltage Vctr and declines, and the frequency of the output signal fout1 of pierce circuit 43 increases; When the frequency hour of the frequency ratio input reference signal fref of output signal fout1, the electric current of charge pump circuit 48 flows into filter circuit 21, controls voltage Vctr and rises, and the frequency of the output signal fout1 of pierce circuit 43 reduces; Above-mentioned comparison procedure is carried out always, until the output signal fout1 of pierce circuit 43 is identical with the frequency of input reference signal fref.As mentioned above, output signal fout1 can be identical with the output signal fout of whole clock generator, also can have certain suitable incidence relation.
Frequency and phase discrimination circuit 49 compares the output signal fout of input reference signal fref and pierce circuit 43, and output is for controlling the signal of charge pump circuit 48.Charge pump circuit 48 is the electric current in inflow direction or outflow direction according to the output signal output of frequency and phase discrimination circuit 49, filter circuit 21 receives the current signal from charge pump circuit 48, and remove the high-frequency noise being included in current signal, produce the control voltage Vctr for controlling pierce circuit 43.Control voltage Vctr control pierce circuit 43 and produce output signal fout1 and fout.Output signal fout1 and input reference signal fref compare again, and this comparison procedure is carried out repeatedly, until output signal fout1 and two signals of input reference signal fref equate.
Furthermore, in the course of work of built-in oscillating circuit, for stablize output signal frequency, reduce costs, the present embodiment adopts closed loop circuit structure, integrated on full sheet, and these deviations of frequency signal are compensated, and produces high-precision frequency signal.The frequency signal of ring oscillator 13 be subject to temperature, the impact of the environment such as process deviation and supply voltage, for example, when assumed temperature rises, control voltage Vctr moment does not change, the frequency of the output signal fout1 of pierce circuit 43 declines, the clock signal clk 1 that so non-overlapped signal generating circuit 44 is exported and the frequency of CLK2 decline, therefore the feedback current Iout that frequency-electric current conversion circuit 45 is exported starts to reduce, and reference current Ib remains unchanged, so the amplitude output signal of current comparator 42 declines, correspondingly, controlling voltage Vctr declines, the frequency of the output signal fout1 of pierce circuit 43 increases with the decline of controlling voltage Vctr, the feedback current Iout that frequency-electric current conversion circuit 45 is exported increases thereupon, thus, negative feedback regulates to be carried out always, until the feedback current Iout of output and reference current Ib equate, be the loop of built-in oscillating circuit again stable till, equally, in the time that temperature declines, also there is identical negative feedback adjustment process, until the loop of built-in oscillating circuit is again stable.
The second embodiment
As shown in Figure 8, the structure of its structure and Fig. 4 is basic identical for the structure of the clock generator of the second embodiment, and difference is to have set up divider circuit 47 and voltage stabilizing generator 46.Wherein, the output of the input connection oscillator circuit 43 of divider circuit 47, the output of divider circuit 47 connects the input of non-overlapped signal generating circuit 44 and the second input of frequency and phase discrimination circuit 49.Voltage stabilizing generator 46 receives an external power source VDD, and the power supply signal VDDA that is translated into stable output uses for the modules in clock generator.In addition, voltage stabilizing generator 46 can also utilize external power source VDD to produce stable reference voltage, for example the first reference voltage Vref, the second reference voltage Vb etc.Wherein, the first reference voltage Vref, the second reference voltage Vb can be identical, also can be different.
In the time of built-in oscillating circuit work, divider circuit 47 carries out after frequency division the output signal fout1 of pierce circuit 43, and the signal fd after frequency division is transferred to non-overlapped signal generating circuit 44.Furthermore, the clock signal clk 1 that non-overlapped signal generating circuit 44 produces and CLK2 are through overfrequency-electric current conversion circuit 45, and increase arranges divider circuit 47 can make frequency-voltage conversion circuit 45 steady operations.
In the time that phase-locked loop circuit is worked, divider circuit 47 carries out after frequency division the output signal fout1 of pierce circuit 43, the signal fd after frequency division is transferred to the second input of frequency and phase discrimination circuit 49.Increase divider circuit 47, can make frequency and phase discrimination circuit 49 steady operations.
More specifically, in actual process production process, the temperature deviation of the frequency of the output signal fout of built-in oscillating circuit is got the main certainly temperature characterisitic of resistance and electric capacity after loop-locking.Conventionally, in actual process the temperature coefficient of electric capacity at every degree Celsius 10
-6inferior magnitude, and the temperature coefficient of single resistance is 10
-3inferior magnitude, so temperature coefficient is mainly determined by resistance-temperature characteristic.In order to reach deviation in 1% in-20 ℃～85 ℃ temperature ranges, need to compensate temperature coefficient of resistance, therefore, the trimming resistors that the basic current of the present embodiment produces in circuit is selected positive temperature coefficient resistor and negative temperature coefficient resister series complementary, makes trimming resistors not be subject to the impact of temperature.
For the clock generator shown in Fig. 8, in the time of built-in oscillating circuit work, in the time that output signal fout stablizes, the frequency of output signal fout is:
Wherein, fout is the frequency of the output signal fout of built-in oscillating circuit, M is the frequency division multiple of divider circuit 47, Cc is that charge and discharge capacitance Cc(is referring to Fig. 6) capacitance, (Rp+Rn) for basic current produces trimming resistors Rp+Rn(in circuit 41 referring to Fig. 5) resistance value, K is proportionality coefficient, and for definite circuit structure, K is constant.
As a preferred embodiment, this clock generator can provide multi-frequency output, for example, can be respectively processor and chip provides clock signal.For example, can regulate or programme by the frequency division multiple M to divider circuit 47, multiple alternative clock frequencies are provided.
Other information of clock generator shown in Fig. 8 can, with reference to the content of aforementioned the first embodiment, repeat no more here.
In sum, the clock generator of the embodiment of the present invention is integrated with built-in oscillating circuit and phase-locked loop circuit, under the requirement that meets systematic function, can considering cost and the requirement of systematic function, and different clock generating circuits is provided.
The above, be only preferred embodiment of the present invention, not the present invention done to any pro forma restriction.Therefore, every content that does not depart from technical solution of the present invention, just according to technical spirit of the present invention to any simple modification made for any of the above embodiments, the conversion that is equal to, all still belong in the protection range of technical solution of the present invention.
Claims (20)
1. a clock generator, is characterized in that, comprising:
Built-in oscillating circuit;
With the phase-locked loop circuit of described built-in oscillating circuit coupling, this phase-locked loop circuit and described built-in oscillating circuit shared oscillator circuit and filter circuit;
Wherein, under the control of enable signal, the output signal that the output signal of described clock generator is this built-in oscillating circuit or the output signal of this phase-locked loop circuit.
2. clock generator according to claim 1, is characterized in that, described built-in oscillating circuit comprises:
Basic current produces circuit, for generation of reference current;
Current comparator, its first input end is connected with the output that described basic current produces circuit;
Described filter circuit, its input connects the output of described current comparator, and this filter circuit carries out filtering to the comparison signal of described current comparator output and controls voltage to produce;
Described pierce circuit, its input connects the output of described filter circuit, and this pierce circuit produces output signal under the control of described control voltage;
Non-overlapped signal generating circuit, its input connects the output of described pierce circuit, and this non-overlapped signal generating circuit produces non-overlapped at least two-way clock signal according to the output signal of described pierce circuit;
Frequency-electric current conversion circuit, its input connects the output of described non-overlapped signal generating circuit, its output connects the second input of described current comparator, the at least two-way clock signal that this frequency-electric current conversion circuit produces described non-overlapped signal generating circuit is converted into feedback current, and this current comparator compares the reference current of this feedback current and the generation of described basic current generation circuit.
3. clock generator according to claim 2, it is characterized in that, described built-in oscillating circuit also comprises: divider circuit, the output of described pierce circuit connects the input of described non-overlapped signal generating circuit via described divider circuit, this frequency divider carries out frequency division to the output signal of described pierce circuit.
4. clock generator according to claim 2, is characterized in that, described basic current produces circuit and comprises:
The first operational amplifier, its first input end receives the first default reference voltage;
The first amplifier tube, its control end connects the output of described the first operational amplifier, and its first end connects power supply, and its second end connects the second input of described the first operational amplifier;
Trimming resistors, the second end of described the first amplifier tube is via described trimming resistors ground connection;
Mirror image circuit, does mirror image to the electric current of described the first amplifier tube of flowing through, and the output of this mirror image circuit produces the output of circuit as described basic current.
5. clock generator according to claim 4, is characterized in that, described trimming resistors comprises positive temperature coefficient resistor and the negative temperature coefficient resister of series connection.
6. clock generator according to claim 4, it is characterized in that, described mirror image circuit comprises one or more mirror image pipes, the control end of these one or more mirror image pipes connects the control end of described the first amplifier tube, the first end of these one or more mirror image pipes connects the first end of described the first amplifier tube, and the second end of these one or more mirror image pipes is as the output of described mirror image circuit.
7. clock generator according to claim 2, is characterized in that, described frequency-electric current conversion circuit comprises:
The second operational amplifier, its first input end receives the second default reference voltage;
The second amplifier tube, its control end connects the output of described the second operational amplifier, and its second end connects the second input of described the second operational amplifier;
The first switch, its first end connects the second end of described the second amplifier tube, and its control end receives the first clock signal of described non-overlapped signal generating circuit output;
Charge and discharge capacitance, its first end connects the second end of described the first switch, its second end ground connection;
Second switch, its first end connects the first end of described charge and discharge capacitance, its second end ground connection;
Electric current output module, connects the first end of described the second amplifier tube, and the first end of described the second amplifier tube is via this electric current output module output feedback current.
8. clock generator according to claim 7, is characterized in that, described frequency-electric current conversion circuit also comprises: filter capacitor, its first end connects the second end of described the second operational amplifier, its second end ground connection.
9. clock generator according to claim 7, is characterized in that, described electric current output module comprises:
The first efferent duct, its first end connects power supply, and its control end connects the first end of described the second amplifier tube;
The second efferent duct, its first end connects the second end of described the first efferent duct, and its second end connects the first end of described the second amplifier tube.
10. clock generator according to claim 9, is characterized in that, described current comparator comprises:
First mirror image tube, its first end connects power supply, and its control end connects the control end of described the first efferent duct;
The second mirror image pipe, its first end connects the second end of described first mirror image tube, and its control end connects the control end of described first mirror image tube, and its second end is as the output of described current comparator;
Limit electric capacity, its first end connects power supply, and its second end connects the second end of described the second mirror image pipe;
Mirror image module, its first mirror connects the second end of described the second mirror image pipe as input, and its second mirror image input receives described basic current and produces the reference current that circuit produces.
11. clock generators according to claim 7, is characterized in that, also comprise: voltage stabilizing generator, and for described the second reference voltage is provided.
12. clock generators according to claim 2, it is characterized in that, the frequency of the output signal of described pierce circuit is affected by environment, when temperature rise, this control voltage instantaneous does not change, the frequency of the output signal of described pierce circuit declines, the frequency of at least two-way clock signal of described non-overlapped signal generating circuit output declines, the feedback current of this frequency-electric current conversion circuit output starts to reduce, and described reference current remains unchanged, so the comparison signal amplitude of this current comparator output declines, the corresponding decline of described control voltage, the frequency of the output signal of described pierce circuit increases with the decline of described control voltage, the feedback current of described frequency-electric current conversion circuit output increases thereupon, thus, negative feedback regulates and continues to carry out, until described feedback current and reference current are equal, till the loop of described built-in oscillating circuit is stablized again.
13. clock generators according to claim 1, is characterized in that, described phase-locked loop circuit comprises:
Frequency and phase discrimination circuit, its first input end receives reference frequency signal, the output signal of this reference frequency signal and described pierce circuit is compared and produce output signal, and the output signal of this frequency and phase discrimination circuit is proportional to the phase difference of the output signal of described reference frequency signal and described pierce circuit;
Charge pump circuit, its input connects the output of described frequency and phase discrimination circuit, and this charge pump circuit is according to the output signal generation current signal of described frequency and phase discrimination circuit;
Described filter circuit, its input connects the output of described charge pump circuit, and described filter circuit filtering produces control signal;
Described pierce circuit, its input connects the output of described filter circuit, and its output connects the second input of described frequency and phase discrimination circuit, and this pierce circuit produces output signal under the control of described control voltage.
14. clock generators according to claim 13, is characterized in that, described phase-locked loop circuit also comprises: divider circuit, the output of described pierce circuit connects the second input of described frequency and phase discrimination circuit via described divider circuit.
15. clock generators according to claim 13, it is characterized in that, the output signal frequency of described pierce circuit is affected by environment, when temperature rise, described control voltage instantaneous does not change, the frequency of the output signal of described pierce circuit declines, the current signal of described charge pump circuit is subject to the adjusting of described frequency and phase discrimination circuit, in the time that the frequency of this reference frequency signal of frequency ratio of the output signal of described pierce circuit is large, the current signal of this charge pump circuit flows out described filter circuit, this control voltage drop, the frequency of the output signal of this pierce circuit increases, when the frequency hour of this reference frequency signal of frequency ratio of the output signal of described pierce circuit, the current signal of this charge pump circuit flows into this filter circuit, and this control voltage rises, and the frequency of the output signal of this pierce circuit reduces, above-mentioned comparison procedure continues to carry out, until the frequency of the output signal of this pierce circuit is identical with the frequency of this reference frequency signal.
16. according to the clock generator described in any one in claim 1 to 15, it is characterized in that, described filter circuit comprises:
The first electric capacity, its first end connects the input of described filter circuit, its second end ground connection;
The first resistance, its first end connects the input of described filter circuit;
The second electric capacity, its first end connects the second end of described the first resistance, its second end ground connection;
The 3rd switch, its first end connects the first end of described the first resistance, its second end connects the second end of described the first resistance, its control end receives the control signal being associated with described enable signal, when the output signal of described clock generator is the output signal of this built-in oscillating circuit, the 3rd switch closure described in described control signal control, when output signal that the output signal of described clock generator is this phase-locked loop circuit, the 3rd switch disconnects described in described control signal control.
17. according to the clock generator described in any one in claim 1 to 15, it is characterized in that, described pierce circuit is ring oscillator, comprise multiple voltage controlled oscillators, the input of described multiple voltage controlled oscillators and the output formation ring-type of connecting successively, the control end of described multiple voltage controlled oscillators links together as the input of described pierce circuit.
18. according to the clock generator described in any one in claim 1 to 15, it is characterized in that, described built-in oscillating circuit and phase-locked loop circuit are integrated in same chip.
19. according to the clock generator described in any one in claim 1 to 15, it is characterized in that, and when described enable signal is logic low, the output signal that the output signal of described clock generator is this built-in oscillating circuit; In the time that described enable signal is logic high, the output signal that the output signal of described clock-signal generator is described phase-locked loop circuit.
20. according to the clock generator described in any one in claim 1 to 15, it is characterized in that, the frequency range of the output signal of described clock generator is set to 27MHZ～49MHZ, for remote-control toy; Or the frequency range of the output signal of described clock generator is set to 315MHZ～433MHZ, for wireless control apparatus; Or the frequency range of the output signal of described clock generator is set to 1MHZ～10MHZ, for infrared remote control equipment or MEMS equipment.
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| CN201410126174.2A CN103873054A (en) | 2014-03-31 | 2014-03-31 | Clock generator |
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