CN202268843U - Low temperature oscillator with high power supply rejection ratio - Google Patents
Low temperature oscillator with high power supply rejection ratio Download PDFInfo
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- CN202268843U CN202268843U CN2011203324254U CN201120332425U CN202268843U CN 202268843 U CN202268843 U CN 202268843U CN 2011203324254 U CN2011203324254 U CN 2011203324254U CN 201120332425 U CN201120332425 U CN 201120332425U CN 202268843 U CN202268843 U CN 202268843U
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Abstract
The utility model discloses a low temperature oscillator with a high power supply rejection ratio. Through a CMOS processing technique, the low temperature oscillator is composed of a constant current and constant voltage generation module, and an oscillation module. A frequency-sable pulse signal having a duty ratio of 50% can be generated without additional arrangement of any signal and element besides a power supply, the ground and an optional reset signal, and the frequency of the signal can be adjusted through changes of parameters of components in a circuit. Except for some occasions which are high in requirement for frequency precision, the low temperature oscillator can replace a crystal oscillator to a certain extent and can be conveniently integrated into other circuits for use without additional increase of base pins.
Description
Technical field
The utility model relates to integrated circuit, particularly integrated oscillator circuit.
Background technology
Oscillating circuit is also claimed signal generating circuit, is the circuit that often uses in a lot of electronic circuits.What for example clock is provided for digital circuit is exactly sort circuit, and the carrier signal that various signals such as radio wave is sent to a distant place is also produced by oscillating circuit.The waveform that oscillating circuit produces has a variety of, like sine wave, square wave, triangular wave, oblique wave etc.Frequency of oscillation is the clock generator that constant oscillating circuit is called digital circuit or system, and its output waveform is generally square wave.
Crystal oscillating circuit is the oscillating circuit of present most popular high accuracy, high stability.Crystal oscillator is a kind of resonating device that utilizes the piezoelectric effect of crystal to process.If on two electrodes of crystal, add an electric field, wafer will produce mechanical deformation; Otherwise, if apply mechanical pressure, then on the corresponding direction of wafer, will produce electric field in the both sides of wafer, this physical phenomenon is called piezoelectric effect.If on the two poles of the earth of wafer, add alternating voltage, wafer will produce mechanical oscillation, and the mechanical oscillation of wafer simultaneously can produce alternating electric field again.In the ordinary course of things, the amplitude of wafer mechanical oscillation and the amplitude of alternating electric field are very small, but when the frequency that adds alternating voltage was a certain particular value, amplitude obviously strengthened, and more much bigger than the amplitude under other frequencies, this phenomenon is called piezoelectric resonator.The resonance frequency of wafer itself is only relevant with cutting mode, geometry, the size of wafer basically, and can do very accurately, so crystal oscillating circuit can obtain very high frequency accuracy and stability.Exactly because but the also character of crystal oscillating circuit itself makes it aspect integrability, have great drawback, can't be compatible with the existing integrated circuits process for machining and manufacturing, must be external.The two ends that the circuit of use crystal oscillator must provide two pins to connect crystal oscillators also need external two ceramic disc capacitors in addition, so just very are unfavorable for reducing the size of circuit board, can't reduce the processing and manufacturing cost.
The RC oscillator also is to use a kind of widely oscillating circuit at present, and it has simple in structure, is convenient to integrated characteristics.The most basic RC oscillating circuit is as shown in Figure 1, by capacitor C, resistance R, by reverser I
1~ I
nDelay unit and discharge tube N that (n is an even number) realizes
1Form.The voltage of supposing capacitor C top crown when initial is 0, and the output signal OUT of circuit also is 0; Capacitor C is through the resistance R charging, and the voltage on electric capacity surpasses I
1Overturn point the time, I
1Output become low level, through after the time-delay of n reverser, output signal OUT becomes high level, while discharge tube N
1Open, to the capacitor C discharge, the voltage on electric capacity is lower than I
1Overturn point the time OUT become low level, discharge tube turn-offs, and so goes round and begins again and realizes vibration.Can find out with its operation principle from the structure of RC oscillating circuit; The frequency of output signal OUT not only receives the influence of processing technology; But also change with the variation of supply voltage, ambient temperature; Therefore the precision and the stability of its frequency are relatively poor, only can be used for the less demanding occasion of frequency accuracy.
Therefore; It is constant how the capacitor charge and discharge electric current keeps under the situation of supply voltage and variation of ambient temperature; How to guarantee that comparator threshold voltage is not with supply voltage and environmental temperature fluctuation; And how the influence of oscillator frequency to be become the difficult problem that pendulum solves in oscillating circuit designers urgent need at the moment through technological fluctuation in the structure optimization reduction integrated circuit processing and manufacturing process.
The utility model content
Adopt crystal oscillating circuit to realize to present oscillating circuit no matter be; Or adopting the RC oscillator to realize all existing the problem of defective, the applicant improves through research, and a kind of high PSRR low temperature oscillator that wafts is provided at present; Can substitute crystal oscillator to a certain extent; And have frequency accuracy and stability that general RC oscillator can't provide, can effectively reduce the processing and manufacturing cost of system, increase the reliability of system.
The technical scheme of the utility model is following:
A kind of high PSRR low temperature oscillator that wafts is connected and composed by constant current constant voltage generation module and oscillation module;
Said constant current constant voltage generation module comprises band-gap reference circuit, follower and current mirror; The output of said band-gap reference circuit is connected with the input of follower, and the output of said follower is connected with the input of current mirror; The output of said band-gap reference circuit is through the upset level of electric resistance partial pressure as comparator in the oscillation module; The output of said current mirror is as the voltage bias that produces the constant capacitance charging current in the oscillation module;
Said oscillation module comprises electric capacity, R-S trigger and two voltage comparators; The output of said current mirror is to the charging of said electric capacity and connect the backward end of said voltage comparator; The said upset level of band-gap reference circuit output connects the end in the same way of voltage comparator; The output of said two voltage comparators is sent to said R-S trigger, said R-S trigger output waveform.
Its further technical scheme is: said constant current constant voltage generation module also comprises biasing circuit; The bias point of said biasing circuit connects the adjustable end of amplifier in said band-gap reference circuit and the follower, for said band-gap reference circuit and follower provide the working point respectively.
Its further technical scheme is: said constant current constant voltage generation module also comprises reset circuit; The respectively base stage of metal-oxide-semiconductor or the adjustable end of amplifier in connecting band gap reference circuit, follower and the current mirror, whether the each several part that is used for controlling the constant current constant voltage generation module works.
Its further technical scheme is: said oscillation module also comprises multistage inverter, is connected to the input and the output of R-S trigger.
The useful technique effect of the utility model is:
One, the utility model makes the frequency of oscillation of oscillator and capacitance discharges electric current irrelevant through the structural design of oscillator; Adopt band-gap reference to produce and supply voltage, the irrelevant current source of ambient temperature again,, just can guarantee that the electric capacity charging current is constant to the electric capacity charging.Frequency accuracy and stability are high, and frequency of oscillation changes small with circuit voltage and ambient temperature.
Two, the unit that compares is selected comparator for use, rather than reverser, its overturn point be through positive-negative input end set not with supply voltage and variation of ambient temperature.
Three, the resistance in the circuit all is to use ratio value basically, and the variation of resistance absolute value is very little to the influence of circuit; Electric capacity is selected stable PIP electric capacity for use, drops to minimum to the influence of circuit technology.
Four, adopt the CMOS processing technology, be easy to integrated; Need not add any pin and control signal (except the optional reset signal, this signal can be with this module shuts down, to reduce power consumption), can produce the impulse wave of frequency accuracy and stability ultra-traditional RC far away oscillating circuit after circuit powers on; Can substitute crystal oscillating circuit in most occasions, can effectively reduce the processing and manufacturing cost of machine system, improve the reliability of system.
Description of drawings
Fig. 1 is the principle schematic of traditional RC oscillating circuit.
Fig. 2 is the theory diagram of the utility model.
Fig. 3 is the circuit diagram of constant current constant voltage generation module in the utility model.
Fig. 4 is the circuit diagram of amplifier X310 among Fig. 3.
Fig. 5 is the circuit diagram of amplifier X307 among Fig. 3.
Fig. 6 is the simulation waveform figure of constant-current source bias voltage.
Fig. 7 is the circuit diagram of oscillation module in the utility model.
Fig. 8 is the simulation waveform figure of frequency of oscillation with mains voltage variations.
Fig. 9 is the simulation waveform figure of frequency of oscillation with variation of ambient temperature.
Embodiment
Further specify below in conjunction with the embodiment of accompanying drawing the utility model.
The mentality of designing of the utility model is to produce a current source I who all has nothing to do with power supply, temperature
REF, and a voltage V who all has nothing to do with power supply, temperature
REF, through electric current I
REFTo the electric capacity charging, with V
REFDividing potential drop compare because charging current I
REFAll irrelevant with power supply and temperature with comparative voltage, the frequency of oscillation that therefore produces also has nothing to do with power supply, ambient temperature.Specifically see following detailed.
As shown in Figure 2, the utility model is made up of constant current constant voltage generation module and oscillation module two parts.
As shown in Figure 3, the constant current constant voltage generation module mainly comprises band-gap reference circuit, follower and current mirror.The output of band-gap reference circuit is connected with the input of follower, and the output of follower is connected with the input of current mirror.The output of band-gap reference circuit is through the upset level of electric resistance partial pressure as comparator in the oscillation module.The output of current mirror is as the voltage bias that produces the constant capacitance charging current in the oscillation module.Also comprise biasing circuit and reset circuit, the adjustable end of amplifier in the bias point connecting band gap reference circuit of biasing circuit and the follower is respectively band-gap reference circuit and follower provides the working point; Reset circuit is the base stage of metal-oxide-semiconductor or the adjustable end of amplifier in connecting band gap reference circuit, follower and the current mirror respectively, and whether the each several part that is used for controlling the constant current constant voltage generation module works.
One, the generation of constant voltage
The generation of constant current and constant voltage signal in the utility model circuit is described below in conjunction with Fig. 3, Fig. 4 and Fig. 5.As everyone knows, band-gap reference is commonly used not with the structure of voltage and variations in temperature in the circuit.Principle according to band-gap reference combines the circuit diagram of Fig. 3 to know; The output voltage of amplifier X307 is:
; Wherein
, n are the area ratio of triode Q306 and triode Q305 emitter.In order to obtain zero-temperature coefficient; Must make
; Get n in the present embodiment and equal 8; Resistance R 303 equals 36K; Resistance R 304 equals 4.95K, at this moment
.V
RefDividing potential drop through resistance R 308 and resistance R 309 just can obtain voltage V
Inp, this voltage and V
RefEqually have good temperature and power supply characteristic, can be used as the upset level of oscillation module comparator.
Two, the generation of constant-current source bias voltage
Manage for a PMOS, when mains voltage variations, as long as guarantee its V
DAnd V
GDifference constant, the drain terminal electric current of this PMOS pipe is just constant.For stability that guarantees pipe work and the influence that does not receive the gate voltage absolute value, also to make pipe work in the saturation region, promptly satisfy V
DS>V
GS-V
THIn Fig. 3, operational amplifier X310 uses as follower, and its output OUT1 equals V
RefCircuit diagram through amplifier X310 among Fig. 4 can see that when mains voltage variations, PMOS pipe MP404 satisfies V
DAnd V
GConstant, the V of difference
DS>V
GS-V
THTwo conditions can provide a constant electric current, drop on voltage OUT1 on the resistance R 409 not with change in voltage; The input of the difference of operational amplifier can compensation temperature influence, so OUT1 has and V
RefIdentical temperature voltage characteristic, OUT2 can be used as the voltage bias that produces constant current.Use the BIA1 of the current mirror generation of forming by PMOS pipe MP311, PMOS pipe MP312, NMOS pipe MN314, NMOS pipe MN315 in the present embodiment, as the voltage bias that produces the constant capacitance charging current in the oscillation module.Fig. 6 is the simulation waveform figure of constant-current source voltage bias in the present embodiment, employing be the 0.35umCMOS of ASMC company process modeling.From oscillogram, can see, when supply voltage changes in the 5V scope V from 2V
DAnd V
GDifference (delta) be 1.19V all the time.
Three, oscillation module
As shown in Figure 7, oscillation module comprises electric capacity, R-S trigger and two voltage comparators.The output of current mirror is to the backward end of electric capacity charging and connection voltage comparator, and the output of band-gap reference circuit is as the end in the same way of upset level connection voltage comparator, and the output of two voltage comparators is sent to the R-S trigger and finally exports waveform.Also comprise multistage inverter, multistage inverter is connected to the input and the output of R-S trigger.
Can see that from the circuit diagram of Fig. 3 and Fig. 7 when the reset signal RES of circuit was low level, entire circuit was in resting state, at this moment BIA1=1.Explain below in conjunction with Fig. 7 how oscillation module works.BIA1 is a high level when initial, and the charging path of capacitor C 607 and capacitor C 620 turn-offs, and reset signal RESN is 1 in addition, and NMOS pipe MN608 and NMOS pipe MN621 open, and make Vinm1, Vinm2 be pulled to low level, all do not have voltage on two electric capacity; This moment, X626Y was 1, and X613Y and CLK are 0.After the reset signal RES of circuit became high level, constant voltage signal Vinp produced, and constant biasing voltage BIA1 sets up, because X613Y is 0, the charging path of capacitor C 620 is opened, and began to capacitor C 620 chargings.When the voltage Vinm2 on the capacitor C 620 surpassed Vinp, the output X622Y of comparator X622 became low level by high level, and X627A becomes low level; X627Y becomes high level; Add that RES and X626A are high level, then X626Y becomes low level, and X613Y and CLK become high level; Capacitor C 620 charging paths turn-off, and discharge path is opened; The charging path of capacitor C 607 was opened when X627Y became high level, began charging, when the voltage on the capacitor C 607 surpasses Vinp; The output switching activity of comparator X609; X626Y becomes high level, and X613Y and CLK become low level, and capacitor C 607 charging paths turn-off; Discharge path is opened, and so goes round and begins again and realizes vibration.Can find out from the structure of circuit, if the discharge time of capacitor C 607 and capacitor C 620 less than the charging interval, frequency of oscillation is just irrelevant with the capacitance discharges time, is only determined by charging interval of electric capacity.Because the two-way of oscillator is just the same, the charging current of employing, the turnover voltage of comparator are irrelevant with power supply and temperature again, therefore finally can obtain frequency and with temperature and mains voltage variations and duty ratio be not 50% square wave.
Fig. 8 is the simulation waveform figure of frequency of oscillation with mains voltage variations.Its occurrence such as following table (temperature is 25 ° of C):
Can know from Fig. 8 and last table, when supply voltage when 2V changes to 5V, oscillator frequency has only changed 2.78%.
Fig. 9 is the simulation waveform figure of frequency of oscillation with variation of ambient temperature.Its occurrence such as following table (supply voltage is 3V):
Can know from Fig. 9 and last table, when temperature when 85 ° of C change to-40 ° of C, frequency of oscillation changes and is merely 183ppm/ ° of C.
The explanation of circuit element value such as involved transistor, resistance capacitance is for the utility model is more readily understood in circuit structure in the foregoing description and the accompanying drawing, is not to be the qualification to the utility model.Can change, improve not breaking away under the utility model aim, the utility model also comprises its equivalent certainly.Other improvement and variation that those skilled in the art directly derive under the prerequisite of the basic design that does not break away from the utility model or associate all should be thought to be included within the protection range of the utility model.
Claims (4)
1. one kind high PSRR low temperature oscillator that wafts is characterized in that: connected and composed by constant current constant voltage generation module and oscillation module;
Said constant current constant voltage generation module comprises band-gap reference circuit, follower and current mirror; The output of said band-gap reference circuit is connected with the input of follower, and the output of said follower is connected with the input of current mirror; The output of said band-gap reference circuit is through the upset level of electric resistance partial pressure as comparator in the oscillation module; The output of said current mirror is as the voltage bias that produces the constant capacitance charging current in the oscillation module;
Said oscillation module comprises electric capacity, R-S trigger and two voltage comparators; The output of said current mirror is to the charging of said electric capacity and connect the backward end of said voltage comparator; The said upset level of band-gap reference circuit output connects the end in the same way of voltage comparator; The output of said two voltage comparators is sent to said R-S trigger, said R-S trigger output waveform.
2. according to the said high PSRR low temperature of claim 1 oscillator that wafts; It is characterized in that: said constant current constant voltage generation module also comprises biasing circuit; The bias point of said biasing circuit connects the adjustable end of amplifier in said band-gap reference circuit and the follower, for said band-gap reference circuit and follower provide the working point respectively.
3. according to the said high PSRR low temperature of claim 1 oscillator that wafts; It is characterized in that: said constant current constant voltage generation module also comprises reset circuit; The respectively base stage of metal-oxide-semiconductor or the adjustable end of amplifier in connecting band gap reference circuit, follower and the current mirror, whether the each several part that is used for controlling the constant current constant voltage generation module works.
4. according to the said high PSRR low temperature of claim 1 oscillator that wafts, it is characterized in that: said oscillation module also comprises multistage inverter, is connected to the input and the output of R-S trigger.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011203324254U CN202268843U (en) | 2011-09-06 | 2011-09-06 | Low temperature oscillator with high power supply rejection ratio |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011203324254U CN202268843U (en) | 2011-09-06 | 2011-09-06 | Low temperature oscillator with high power supply rejection ratio |
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| Publication Number | Publication Date |
|---|---|
| CN202268843U true CN202268843U (en) | 2012-06-06 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2011203324254U Expired - Fee Related CN202268843U (en) | 2011-09-06 | 2011-09-06 | Low temperature oscillator with high power supply rejection ratio |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102347728A (en) * | 2011-09-06 | 2012-02-08 | 无锡海威半导体科技有限公司 | Oscillator with high power supply rejection ratio and low temperature wave |
| WO2022052594A1 (en) * | 2020-09-08 | 2022-03-17 | 长鑫存储技术有限公司 | Oscillating circuit |
| US11632079B2 (en) | 2020-09-08 | 2023-04-18 | Changxin Memory Technologies, Inc. | Oscillating circuit |
-
2011
- 2011-09-06 CN CN2011203324254U patent/CN202268843U/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102347728A (en) * | 2011-09-06 | 2012-02-08 | 无锡海威半导体科技有限公司 | Oscillator with high power supply rejection ratio and low temperature wave |
| CN102347728B (en) * | 2011-09-06 | 2014-03-05 | 无锡海威半导体科技有限公司 | Oscillator with high power supply rejection ratio and low temperature wave |
| WO2022052594A1 (en) * | 2020-09-08 | 2022-03-17 | 长鑫存储技术有限公司 | Oscillating circuit |
| US11632079B2 (en) | 2020-09-08 | 2023-04-18 | Changxin Memory Technologies, Inc. | Oscillating circuit |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20120606 Termination date: 20140906 |
|
| EXPY | Termination of patent right or utility model |