Summary of the invention
It is unfavorable for that expanding to higher order function obtains more for above-mentioned existing n function generating circuit is limited by noise
High order degree of accuracy and be not suitable for the situation of alleviating distention in middle-JIAO heart temperature drift for existing function generating circuit, it is an object of the invention to
A kind of simulation higher power function generating circuit for crystal oscillator temperature-compensating is provided.It is one be suitable to integrated, low noise, towards
The high math power function generating circuit of alleviating distention in middle-JIAO heart temperature drift scope, is very suitable for the crystal oscillator to high-precision requirement and carries out temperature
Degree compensates.
In order to reach foregoing invention purpose, technical scheme realizes as follows:
A kind of simulation higher power function generating circuit for crystal oscillator temperature-compensating, it is structurally characterized in that, it includes successively
Temperature sensor, power function current generating circuit, trans-impedance amplifier and the voltage adder connected.Temperature sensor is by will outward
Portion's temperature transition becomes corresponding linear function of voltage to send into the input of power function current generating circuit, and power function electric current produces
Circuit converts information into the higher-order function curve of correspondence and is converted to voltage by trans-impedance amplifier, then passes through voltage adder
It is summed into required voltage with function of first order, zeroth order calibration function.Described power function current generating circuit includes i+j with emitter-base bandgap grading
Degenerative ambipolar class amplitude limit differential pair, wherein i is greater than the integer equal to 4, and j is the integer more than or equal to 1.
Described j differential pair is used for low temperature model as extra compensation circuit during alleviating distention in middle-JIAO heart temperature drift scope
Enclosing and more precisely compensate for, pipe is constituted by bipolar transistor by the input difference in j differential pair with tail current source.
One input of described i differential pair is jointly connected with the outfan of temperature sensor, another input
It is connected with the constant reference voltage source being gradually increased successively, by the class amplitude limit difference amplifier in differential pair circuit, voltage is turned
It is changed to electric current.Wherein, the first and second difference amplifiers are arranged to input identical signal and export contrary polarity, remaining
(i-2) output of individual difference channel has identical with the first difference amplifier output and that the output of the second difference amplifier is contrary pole
Property, the negative feedback voltage current converter consisted of amplifier and resistance is converted to difference current, when by output node, enters
Row is added, and obtains n rank power function electric current.
In above-mentioned simulation higher power function generating circuit, the constant reference voltage of described input is less than the center temperature set
Each differential pair correspondence of the temperature sensor output voltage that degree is corresponding generates the power function of high temperature range.The constant reference electricity of input
Each differential pair correspondence of the temperature sensor output voltage that pressure is corresponding more than the central temperature set generates the power letter of low temperature range
Number, the difference of the temperature sensor output voltage that the constant reference voltage of input is corresponding equal or close to the central temperature set
Correspondence is offseted first order, generates smooth middle temperature range part.
In above-mentioned simulation higher power function generating circuit, the difference amplifier of described generation high temperature power function is low with generation
The output of the difference amplifier of isothermal segment power function has contrary polarity, and eliminates the difference of isothermal segment power function in generation
Amplifier.
In above-mentioned simulation higher power function generating circuit, described j differential pair, as extension low temperature range differential pair, is used
Edge result in matching low temperature range.J differential pair has and generates the output of differential pair of low temperature range in i differential pair
There is identical polarity.J differential pair one end is connected with temperature sensor output, and the other end is connected with constant reference voltage
Connect, and this constant reference voltage is greater than equal to the value of constant reference level in aforementioned i differential pair.
In above-mentioned simulation higher power function generating circuit, described circuit also includes replicate compensating current element in order to eliminate
The zeroth order skew introduced in i+j differential pair.
In above-mentioned simulation higher power function generating circuit, described higher power function generating circuit is divided into odd-order power function
There is circuit and even-order power function generation circuit.Odd-order power function generation circuit replicates the current amplitude of compensating current element
Equal to the sum of j extension low temperature range differential-pair tail current, even-order power function generation circuit replicates the electricity of compensating current element
Stream amplitude is equal to the sum of i+j differential-pair tail current.
In above-mentioned simulation higher power function generating circuit, five rank power functions in described higher power function generating circuit are sent out
Raw circuit, is arranged to i=6 and j=1.Wherein the constant level reference voltage of first and second ambipolar differential pair input is identical,
The constant level reference voltage of the 3rd to the 7th ambipolar differential pair input sequentially increases, the constant level of the 4th differential pair input
Reference voltage is less than the reference voltage of the constant level of first, second ambipolar differential pair input, the perseverance of the 5th differential pair input
Determine the level reference voltage reference voltage less than the constant level of first, second ambipolar differential pair input, the 7th ambipolar difference
Divide the constant level reference voltage with maximum.Quadravalence power function generation circuit in described higher power function generating circuit,
It is arranged to i=6 and j=1.Wherein the constant reference level of the first to the 7th input sequentially increases.Described higher power function occurs
Three rank power function generation circuit in circuit, are arranged to i=4 and j=1.Wherein first and second ambipolar differential pair inputs
Constant level reference voltage is identical, and the constant level reference voltage of the 3rd to the 5th ambipolar differential pair input sequentially increases, the
The constant level reference voltage of three differential pair inputs is less than the reference electricity of the constant level of first, second ambipolar differential pair input
Pressure, the constant level that the constant level reference voltage of the 4th differential pair input inputs less than first, second ambipolar differential pair
Reference voltage, the 5th ambipolar differential pair has the constant level reference voltage of maximum.
In above-mentioned simulation higher power function generating circuit, described five rank power function generation circuit replicate compensating current element
Current amplitude equal to the current amplitude in the 7th ambipolar differential-pair tail current source.Described three rank power function generation circuit replicate
The current amplitude of compensating current element is equal to the current amplitude in the 5th ambipolar differential-pair tail current source.Described quadravalence power function occurs
Circuit replicates the sum equal to first to the 7th differential-pair tail current of the current amplitude in compensating current element.
Due to the fact that and have employed said structure, single n rank power function electric current can be obtained.By using simple ratio
The trans-impedance amplifier that amplifying circuit is constituted, the power function electric current conversion that can easily power function electric current-producing device be produced
Power function voltage needed for one-tenth, for carrying out temperature-compensating to crystal, it is adaptable to broader central temperature point T0Temperature drift
The circuit of more than three times higher order functionalities of scope.Use the present invention, can effectively reduce the noise of circuit, and obtain higher
Calibration accuracy.
The invention will be further described with detailed description of the invention below in conjunction with the accompanying drawings.
Detailed description of the invention
Referring to Fig. 1 and Fig. 2, the present invention includes the temperature sensor being sequentially connected with, power function current generating circuit, puts across resistance
Big device and voltage adder.Temperature sensor sends into power function by the linear function of voltage that external temperature is converted into correspondence
The input of current generating circuit.Power function current generating circuit convert information into correspondence higher-order function curve and pass through across
Impedance amplifier is converted to voltage, then is summed into required voltage by voltage adder and function of first order, zeroth order calibration function.Power letter
Number current generating circuit includes i+j the ambipolar class amplitude limit differential pair with emitter degeneration, and wherein i is greater than equal to 4
Integer, j is the integer more than or equal to 1.J differential pair is as extra compensation circuit during alleviating distention in middle-JIAO heart temperature drift scope
For more precisely compensating for low temperature range, the input difference in j differential pair is to managing with tail current source by ambipolar
Transistor is constituted.One input of i differential pair is jointly connected with the outfan of temperature sensor, and another input depends on
Constant reference voltage source that is secondary and that be gradually increased is connected, and is converted the voltage into by the class amplitude limit difference amplifier in differential pair circuit
For electric current.Wherein, the first and second difference amplifiers are arranged to input identical signal and export contrary polarity, remaining
(i-2) output of individual difference channel has identical with the first difference amplifier output and that the output of the second difference amplifier is contrary pole
Property, the negative feedback voltage current converter consisted of amplifier and resistance is converted to electric current, when by output node, carries out phase
Add, obtain n rank power function electric current.
Referring to Fig. 3, it is illustrated by with five power function generating circuits for the embodiment of odd-order power function generator.Five times
Function generating circuit is by from QA-QGSeven class amplitude limit cascode emitter degeneration differential pairs and QCPThe compensating current element group constituted
Becoming, wherein current mirroring circuit 1 constitutes the tail current source of differential pair.In current mirror, circuit 2 includes bipolar transistor Q0, its collection
Electrode is connected to bipolar transistor QHBase stage, and be connected to positive source V by constant current sourceDD;Its base stage is with bipolar
Transistor npn npn QHEmitter stage be connected, its emitter stage pass through feedback resistance R0It is connected to ground VSS;Bipolar transistor QHColelctor electrode
With VDDIt is connected, for bipolar transistor parameter beta is made suppression with the impact of technique Yu variations in temperature.Circuit in this current mirror
2 also include respective base stage and bipolar transistor Q0Base stage be connected eight bipolar transistor Q1To Q8, their emitter stage
It is connected to ground V also by corresponding feedback resistanceSS;Current mirroring circuit 1 provides for class amplitude limit cascode emitter feedback differential pair 4A-4G
Tail current source;Class amplitude limit differential pair negative terminal output voltage is connected to amplifier OP1Positive input terminal, wherein, amplifier OP1With PMOS
MP1And resistance R9BConstitute current/charge-voltage convertor 3.In current/charge-voltage convertor 3, amplifier OP1Negative terminal with
PMOS MP1Source be connected, and by resistance R9BIt is connected on power vd D;Amplifier OP1Output be connected to PMOS MP1's
Grid, PMOS MP1Drain electrode be outfan, and be connected with the positive output end of differential pair.
Class amplitude limit differential amplifier circuit 4A is the cascode differential pair structure typically with emitter degeneration.Differential amplification electricity
The differential pair of road 4A is by bipolar transistor QA1And QA2Constitute, respectively via serial Feedback resistance RA1And RA2It is connected to current mirror
The bipolar transistor Q of middle circuit 25Colelctor electrode.Input signal VINIt is added to transistor QA1Base stage on, constant level reference
Voltage VREFMIt is added to transistor QA2Base stage on.Bipolar transistor QA2Colelctor electrode by sampling resistor R9AIt is connected to electricity
Source positive terminal VDD, meanwhile, QA1Colelctor electrode be connected to the input of Voltage-current conversion 3 as the positive voltage output end of differential pair
End.
Similarly, class amplitude limit differential amplifier circuit 4C, 4D, 4E, 4F, 4G also have identical structure, its positive input terminal QC1、
QD1、QE1、QF1、QG1Base stage all and QA1Base stage be connected as the input of whole circuit, with the output phase of temperature sensor
Even;QC1、QD1、QE1、QF1、QG1Colelctor electrode be connected, and be connected to the input of Voltage-current conversion 3.Class amplitude limit differential amplification
The negative input end transistor Q of circuit 4C, 4D, 4E, 4F, 4GC2、QD2、QE2、QF2、QG2Base stage input respectively constant reference electricity
Pressure VREFL1、VREFL2、VREFH1、VREFH2、VREFH3。QC2、QD2、QE2、QF2、QG2Colelctor electrode be connected, and by resistance R9AWith power supply
VDDIt is connected.Wherein, it is contemplated that when inflection temperature T0When offseting bigger, the asymmetric situation of flex point both sides curve strengthens, and increases
The differential pair 4G that compensates for close call, and by QCPIt is inclined to eliminate zero degree component that branch road provides a compensation electric current
Difference.
The structure of class amplitude limit differential amplifier circuit 4B is the most special, its input and class amplitude limit differential amplifier circuit 4A
Compare and have anti-phase feature.Input signal VINIt is added to transistor QB2Base stage on, constant level reference voltage VREFMAdded
To transistor QB1Base stage on.Bipolar transistor QB2Colelctor electrode by sampling resistor R9AIt is connected to power positive end VDD, with
Time, QB1Colelctor electrode be connected to the input of current/charge-voltage convertor 3 as the positive voltage output end of differential pair.Certainly,
QB1And QB2Respectively via serial Feedback resistance RB1And RB2It is connected to the bipolar transistor Q of circuit 2 in current mirror4Colelctor electrode.
Owing to the input of class amplitude limit differential amplifier circuit 4B is contrary with class amplitude limit differential amplifier circuit 4A, so their output also has
There is anti-phase feature.
Notice, input the reference voltage V to class amplitude limit differential amplifier circuit 4A to 4GREFH3To VREFL1Size have
Certain feature.In view of input signal VIN is the class linear function with temperature monotone decreasing, reference voltage VREFH3To VREFL1Big
Little it is set to, VREFH3>VREFH2>VREFH1>VREFM>VREFL1>VREFL2.Wherein VREFHIt is fitted for low temperature part, VREFLPin
High-temperature part is fitted.
Now it is specifically described the operation principle of foregoing circuit.
The most individually consider the situation of a differential pair circuit, as shown in Figure 4.At input circuit, can by Kirchhoff's theorem
To obtain,
By Ebers-Moll model,
Ignore the mismatch case between audion, thus available,
Also,
To sum up can obtain,
Work as VIN-VREFMMore than 3VTTime, because QA2Cut-off, and another transistor of all of current direction, therefore colelctor electrode is electric
Stream almost with VIN-VREFMUnrelated.Further, V is only worked asIN-VREFMLess than VTTime, electric current is close to linearly.Thus obtain output electricity
The value of pressure,
So, output voltage
Voltage properties is as shown in Figure 7.
Add now emitter feedback resistance, as shown in Figure 5.As input voltage VINWhen being sufficiently smaller than reference voltage, now,
QA1Enter cut-off region, pass through QA1Electric current be 0.Now flow through QA2Emitter current be ITAILA, it is possible to think addition emitter-base bandgap grading
Feedback resistance, expands the range of linearity of electric current to I0RA1+3VT。
Along with VINIt is gradually increased, QA1Entering amplification region, due to the impact of feedback resistance, output electric current will the most linearly increase
Add, corresponding QA2Output electric current IC2Start linear minimizing.When
Time, QA2Cut-off, IC2=0, the most all of tail current all flows through QA1, IC1=ITAILA, as shown in Figure 5.Now, defeated
Go out differential voltage
Add now current/charge-voltage convertor, as shown in Figure 6.In figure 6, QA2Colelctor electrode connect amplifier OP1Just
Input, and amplifier OP1Negative input end by resistance R9BIt is connected to VDDOn, be equivalent to the resistance R in difference channel Fig. 59BQuilt
Current/charge-voltage convertor 3 substitutes.It is similar to the situation of the cascode differential pair of emitter degeneration, IC1With IC2Still have identical
Current characteristics, as shown in Figure 5.Now, being similar to amplitude limiter circuit, the voltage of node A is limited in identical with reference voltage, no
Be herein A point voltage by amplifier OP1Clamper to QA2Collector voltage identical.This voltage passes through resistance R9BChange into
Electric current IC2Identical current value, and flow through PMOS MP1.As it was previously stated, IC1With IC2Current characteristics identical with Fig. 5.According to
Aforementioned formula (15) (16), exports electric current IOUTBe equivalent to former differential output voltage VODBy resistance R9BChange into the shape of electric current
Formula, i.e.
Its current characteristics is as shown in Figure 8.
The operation principle of five rank power function current generating circuits is discussed in detail below.As it was previously stated, five rank power function electric currents
Produce that circuit can be regarded as being divided by the current generation section for high-temperature part, the current generation section of low temperature part is divided and middle temperature portion
The current generation section divided is grouped into, and circuit diagram is as shown in Figure 3. in five rank power function current generating circuits, and differential pair 4A, 4B structure
Having become the electric current of middle isothermal segment, differential pair 4C, 4D create the current component of high-temperature part, and 4E, 4F, 4G constitute low-temp. portion
The current component divided, wherein differential pair 4G is the extension low-temperature current component for eliminating unsymmetry.The output of whole electric current
Performance plot is as shown in Fig. 9 to Figure 14, and wherein solid line is the value that vertical pivot represents, dotted line is the component of each differential pair output.
Now different temperature ranges is discussed respectively.First considering differential pair 4A and the situation of differential pair 4B, they produce
Less electric current is varied with temperature in having given birth to mesophilic range.As it was previously stated, the electric current that differential pair 4A circuit produces is as shown in figure 19.
Noticing in Fig. 3 circuit, the output polarity of differential pair 4B circuit is contrary with differential pair 4A circuit, therefore produces differential pair 4B circuit
Electric current be adjusted, produce the first order component in electric current eliminating differential pair 4A circuit.As it was previously stated, work as VIN-VREFM=
ITAILBRB+3VTIt is linear segment and the critical point of an input pipe entrance cut-off region.Therefore can be by adjusting reason ITAILBRB's
Value, is adjusted the position of critical point.In differential pair 4B circuit, by using a big ITAILBRBValue, will be linear
The expanded range of part is in the range of whole VIN, say, that obtained the function of first order in the range of a total temperature, as schemed
Shown in 10, Fig. 9 with Figure 10 is overlapped, it is possible to export the smooth output electric current of electric current in obtaining a medium temperature bent
Line.
Now consider the situation of high-temperature part.When the temperature is low, now the value of VIN is much larger than VREFL1、VREFL2。QC1、QD1
Work in amplification region, and QC2, QD2 end.Now output electric current is respectively-ITAILC,-ITAILD.Along with the rising of temperature, VIN
Value be gradually lowered, when the value of VIN is less than VREFL1+ITAILCRC+3VTTime, now QC2 conducting, output electric current is with temperature linearly
Change, as shown in figure 11.It is similar to therewith, when the value of VIN is less than VREFL2+ITAILDRD+3VTTime, audion QD2 turns on, output electricity
Stream linearly changes with temperature, as shown in figure 11.It is overlapped can be obtained by Figure 11 solid line institute to two-way electric current at outfan
Show current characteristics, added up by the high-temperature part with Fig. 9, Figure 10, it is possible to simulate the high-temperature part of five rank power functions.
Low temperature part is slightly more complex.When temperature is higher, now VINValue much smaller than VREFH1、VREFH2。QE2、QF2Work
Make in amplification region, and QE1、QF1Cut-off.Now output electric current is respectively ITAILE, ITAILF.Along with the reduction of temperature, the value of VIN by
Edge up height, when the value of VIN is more than VREFH1-ITAILERE-3VTTime, now QE1Conducting, output electric current linearly changes with temperature, as
Shown in Figure 12.It is similar to therewith, when the value of VIN is more than VREFH2+ITAILFRF+3VTTime, audion QF1Conducting, output electric current is with temperature
Linearly change, as shown in figure 12.At outfan, two-way electric current is overlapped can be obtained by Figure 12 electric current shown in solid special
Property, added up by the low temperature part with Fig. 9, Figure 10, it is possible to simulate the low temperature part of five rank power functions.
As it was previously stated, when center temperature drift is beyond the scope of 25-30 DEG C, now under low temperature state maximum with the highest
The difference of the extreme value of temperature can significantly strengthen, and now has to by being adjusted low temperature part increase differential pair 4G.Such as figure
Shown in 13, increase differential pair and can introduce a constant term deviation or referred to as zeroth order deviation, in order to this constant term is made up,
Introduce QCPBranch road, tail current is set to identical and anti-phase with the tail current source amplitude of differential pair 4G, so can be propped up by 4G
The zeroth order electric current that road produces passes through QCPBranch road is connected to ground, to realize calibrating zeroth order deviation.It is in fact possible to by increasing
The method adding difference channel and compensate electric current obtains broader temperature compensation range and higher precision.
By differential pair 4A to 4G, and QCPThe electric current of place branch road is added the five rank power function electricity that can obtain linear fit
Stream IOUT, as shown in figure 14.
Now, it is illustrated by with bipyramid function generating circuit for the example of even-order power function generator.Such as Figure 15 institute
Showing, described biquadratic function generation circuit is by from QA-QGSeven class amplitude limit cascode emitter degeneration differential pairs and QCPThe benefit constituted
Repaying current source composition, the tail current source that wherein current source circuit 1 is differential pair provides electric current.Current mirroring circuit 2 includes ambipolar
Transistor Q0, its colelctor electrode is connected to bipolar transistor QHBase stage, and be connected to positive source V by constant current sourceDD;
Its base stage and bipolar transistor QHEmitter stage be connected, its emitter stage pass through feedback resistance R0It is connected to ground VSS;Ambipolar crystalline substance
Body pipe QHColelctor electrode and VDDIt is connected, for bipolar transistor parameter beta is made suppression with the impact of technique Yu variations in temperature.
This current mirroring circuit 2 also includes respective base stage and bipolar transistor Q0Base stage be connected eight bipolar transistor Q1To Q8,
Their emitter stage is connected to ground V also by corresponding feedback resistanceSS;This current mirroring circuit 2 is class amplitude limit differential amplifier circuit
4A-4G provides tail current source;Class amplitude limit differential pair negative terminal output voltage is connected to amplifier OP1Positive input terminal, wherein, amplifier OP1
With PMOS MP1And resistance R9BConstitute current/charge-voltage convertor 3.In current/charge-voltage convertor 3, amplifier OP1's
Negative terminal and PMOS MP1Source be connected, and by resistance R9BIt is connected on power vd D;Amplifier OP1Output be connected to PMOS
Pipe MP1Grid, PMOS MP1Drain electrode be outfan, and be connected with the positive output end of differential pair.
Differential pair connected mode in bipyramid function generating circuit is similar with five rank power functions, but its low temperature part is with high
The differential pair of isothermal segment is anti-phase, and is even function in view of even-order power function, has symmetry.Therefore middle isothermal segment can lead to
It is compensated by too low isothermal segment with the value of high-temperature part differential pair, and repays electric current without adding extra middle temperature compensation.Existing
Quadravalence power function produces circuit connection be described as follows.
Class amplitude limit differential amplifier circuit 4D is the cascode differential pair structure typically with emitter degeneration.Class amplitude limit difference
The differential pair of amplifying circuit 4D is by bipolar transistor QD1And QD2Constitute, respectively via serial Feedback resistance RD1And RD2It is connected to
The bipolar transistor Q of circuit 2 in current mirror5Colelctor electrode.Input signal VINOutfan as temperature sensor is added to
Transistor QD1Base stage on, constant level reference voltage VREFL1It is added to transistor QD2Base stage on.Bipolar transistor QD2's
Colelctor electrode passes through sampling resistor R9AIt is connected to power positive end VDD, meanwhile, QD1Colelctor electrode as differential pair positive voltage export
End is connected to the input of current/charge-voltage convertor 3.
Similarly, class amplitude limit differential amplifier circuit 4E, 4F, 4G also have identical structure, its positive input terminal QE1、QF1、QG1
Base stage all and QD1Base stage be connected as the input of whole circuit, be connected with the output of temperature sensor, QD1、QE1、QF1、
QG1Colelctor electrode be connected, and be connected to the input of current/charge-voltage convertor 3.Class amplitude limit differential amplifier circuit 4E, 4F, 4G
Negative input end transistor QE2、QF2、QG2Base stage input constant reference voltage V of low temperature part respectivelyREFH1、VREFH2、
VREFH3。QD2、QE2、QF2、QG2Colelctor electrode be connected, and by resistance R9AWith power supply VDDIt is connected.Wherein, it is contemplated that when flex point temperature
Degree T0When offseting bigger, the asymmetric situation of flex point both sides curve strengthens, and adds the difference compensated for close call
To 4G, and at QCPBranch road provides and compensates electric current to eliminate zero degree component deviation in view of adding.
Input and the difference of matching low temperature part for matching high-temperature portion classification amplitude limit differential amplifier circuit 4A, 4B, 4C
To the anti-phase feature that compares.Input signal VINIt is added to transistor QA2、QB2、QC2Base stage on, QA1、QB1、QC1Base
Pole inputs constant reference voltage V of high-temperature part respectivelyREFL1、VREFL2、VREFL3.Bipolar transistor QA2、QB2、QC2Current collection
Sampling resistor R is passed through in pole9AIt is connected to power positive end VDD, meanwhile, QA1、QB1、QC1Colelctor electrode as the positive voltage of differential pair
Outfan is connected to the input of current/charge-voltage convertor 3.
Notice, input the reference voltage V to class amplitude limit differential amplifier circuit 4A to 4GREFH3To VREFL1Size have
Certain feature.In view of input signal VIN is the class linear function with temperature monotone decreasing, reference voltage VREFH3To VREFL1Big
Little it is set to, VREFH3>VREFH2>VREFH1>VREFM>VREFL1>VREFL2.Wherein VREFHIt is fitted for low temperature part, VREFLPin
High-temperature part is fitted.
The operation principle of quadravalence power function current generating circuit is discussed in detail below.As it was previously stated, quadravalence power function electric current
Produce that circuit can be regarded as being divided by the current generation section for high-temperature part, the current generation section of low temperature part is grouped into.Electricity
Road figure is as shown in Figures 4 to 6.Referring to Figure 15, in quadravalence power function current generating circuit, differential pair class amplitude limit differential amplification electricity
Road 4A, 4B, 4C create the current component of high-temperature part, and class amplitude limit differential amplifier circuit 4D, 4E, 4F, 4G constitute low temperature
The current component of part, wherein differential pair 4G is the extension low-temperature current component for eliminating unsymmetry.
When the temperature is low, now the value of VIN is much larger than VREFL1。QA2Work in amplification region, and QA1Cut-off.Now export
Electric current is respectively ITAILA.Along with the rising of temperature, the value of VIN is gradually lowered, when the value of VIN is less than VREFL1+ITAILCRC+3VTTime,
Now QA1Conducting, output electric current linearly changes with temperature, and is gradually reduced along with the increase of temperature.It is similar to therewith, works as temperature
When spending higher, now VINValue much smaller than VREFH1。QD2Work in amplification region, and QD1Cut-off.When the value of VIN is more than VREFH1-
ITAILERE-3VTTime, audion QD1Conducting, output electric current linearly changes with temperature, and gradually subtracts along with the reduction of temperature
Little, as shown in Figure 16 to Figure 21.So class amplitude limit differential amplifier circuit 4A, 4D output electric current and may be constructed as shown in figure 16
Shape.It is similar to therewith, due to VREFH3>VREFH2>VREFH1>VREFM>VREFL1>VREFL2, differential pair class amplitude limit differential amplifier circuit
4B, 4E output electric current and may be constructed shape as shown in figure 17, differential pair class amplitude limit differential amplifier circuit 4C, 4F's is defeated
Go out electric current and may be constructed shape as shown in figure 18.
As it was previously stated, when center temperature drift is beyond the scope of 25-30 DEG C, now under low temperature state maximum with the highest
The difference of the extreme value of temperature can significantly strengthen, and now has to by low temperature part is increased differential pair class amplitude limit differential amplifier circuit
4G is adjusted.As shown in figure 19.Unlike five rank power function current occuring circuits, owing to quadravalence power function electric current is sent out
In raw circuit, the differential pair of matching low temperature range and the output electric current of the differential pair circuit of high temperature range are equal under nonlinear situation
More than zero, so zero-order error can be formed.For herein, the design compensating current branch just seems comparatively simple and clear,
Even
Herein, it is illustrated by as a example by three rank power function generation circuit.As shown in figure 22, described function of third order generation circuit
By from QA-QESeven class amplitude limit cascode emitter degeneration differential pairs and QCPThe compensating current element composition constituted, wherein current source
The tail current source that circuit 1 is differential pair provides bias current.In current mirror, circuit 2 includes bipolar transistor Q0, its colelctor electrode
It is connected to bipolar transistor QHBase stage, and be connected to positive source V by constant current sourceDD;Its base stage and ambipolar crystalline substance
Body pipe QHEmitter stage be connected, its emitter stage pass through feedback resistance R0It is connected to ground VSS;Bipolar transistor QHColelctor electrode with
VDDIt is connected, for bipolar transistor parameter beta is made suppression with the impact of technique Yu variations in temperature.Circuit 2 in this current mirror
Also include respective base stage and bipolar transistor Q0Base stage be connected eight bipolar transistor Q1To Q6, their emitter stage
It is connected to ground V also by corresponding feedback resistanceSS;This current mirroring circuit 2 provides tail electricity for class amplitude limit differential amplifier circuit 4A-4E
Stream source;Class amplitude limit differential pair negative terminal output voltage is connected to amplifier OP1Positive input terminal, wherein, amplifier OP1With PMOS MP1With
And resistance R9BConstitute current/charge-voltage convertor 3.In current/charge-voltage convertor 3, amplifier OP1Negative terminal and PMOS
MP1Source be connected, and by resistance R9BIt is connected to power supply VDDOn;Amplifier OP1Output be connected to PMOS MP1Grid,
PMOS MP1Drain electrode be outfan, and be connected with the positive output end of differential pair.
Class amplitude limit differential amplifier circuit 4A is the cascode differential pair structure typically with emitter degeneration.Class amplitude limit difference
The differential pair of amplifying circuit 4A is by bipolar transistor QA1And QA2Constitute, respectively via serial Feedback resistance RA1And RA2It is connected to
The bipolar transistor Q of current mirroring circuit 25Colelctor electrode.Input signal VINIt is added to transistor QA1Base stage on, constant level
Reference voltage VREFMIt is added to transistor QA2Base stage on.Bipolar transistor QA2Colelctor electrode by sampling resistor R9AConnect
To power positive end VDD, meanwhile, QA1Colelctor electrode be connected to Voltage-current conversion electricity as the positive voltage output end of differential pair
The input on road 3.
Similarly, class amplitude limit differential amplifier circuit 4C, 4D, 4E also have identical structure, its positive input terminal QC1、QD1、QE1
Base stage all and QA1Base stage be connected as the input of whole circuit, be connected with the output of temperature sensor, QC1、QD1、QE1's
Colelctor electrode is connected, and is connected to the input of current/charge-voltage convertor 3.Class amplitude limit differential amplifier circuit 4C, 4D, 4E's is negative
Input side transistor QC2、QD2、QE2Base stage input constant reference voltage V respectivelyREFL1、VREFH1、VREFH2。QC2、QD2、QE2's
Colelctor electrode is connected, and by resistance R9AWith power supply VDDIt is connected.Wherein, it is contemplated that when inflection temperature T0When offseting bigger, flex point
The asymmetric situation of both sides curve strengthens, and adds the class amplitude limit differential amplifier circuit 4E compensated for close call, and
By QCPBranch road provides one and compensates electric current to eliminate zero degree component deviation.
The structure of class amplitude limit differential amplifier circuit 4B is the most special, its input and class amplitude limit differential amplifier circuit 4A
Compare and have anti-phase feature.Input signal VINIt is added to transistor QB2Base stage on, constant level reference voltage VREFMAdded
To transistor QB1Base stage on.Bipolar transistor QB2Colelctor electrode by sampling resistor R9AIt is connected to power positive end VDD, with
Time, QB1Colelctor electrode be connected to the input of current/charge-voltage convertor 3 as the positive voltage output end of differential pair.Certainly,
QB1And QB2Respectively via serial Feedback resistance RB1And RB2It is connected to the bipolar transistor Q of circuit 2 in current mirror4Colelctor electrode.
Owing to the input of class amplitude limit differential amplifier circuit 4B is contrary with class amplitude limit differential amplifier circuit 4A, so their output also has
There is anti-phase feature.
Notice, input the reference voltage V to class amplitude limit differential amplifier circuit 4A to 4GREFH2To VREFL1Size have
Certain feature.In view of input signal VIN is the class linear function with temperature monotone decreasing, reference voltage VREFH3To VREFL1Big
Little it is set to, VREFH2>VREFH1>VREFM>VREFL1.Wherein VREFHIt is fitted for low temperature part, VREFLFor high-temperature part
It is fitted.
The operation principle of three rank power function current generating circuits is discussed in detail below.As it was previously stated, three rank power function electric currents
Produce that circuit can be regarded as being divided by the current generation section for high-temperature part, the current generation section of low temperature part is divided and middle temperature portion
The current generation section divided is grouped into.Circuit diagram as shown in figure 22, in five rank power function current generating circuits, put by class amplitude limit difference
Big circuit 4A, 4B constitute the electric current of middle isothermal segment, and class amplitude limit differential amplifier circuit 4C creates the current component of high-temperature part,
And class amplitude limit differential amplifier circuit 4E, 4D constitute the current component of low temperature part, wherein class amplitude limit differential amplifier circuit 4E is
For eliminating the extension low-temperature current component of unsymmetry.The output characteristics figure of whole electric current is as shown in Figure 23 to Figure 28, wherein
Solid line is the value that vertical pivot represents, dotted line is the component of each differential pair output.
Now different temperature ranges is discussed respectively.First consider the situation of class amplitude limit differential amplifier circuit 4A, 4B, it
Create mesophilic range in vary with temperature less electric current.As it was previously stated, the electricity that class amplitude limit differential amplifier circuit 4A produces
Stream is as shown in figure 23.Notice in Figure 22 circuit, the output polarity of class amplitude limit differential amplifier circuit 4B circuit and class amplitude limit difference
Amplifying circuit 4A is contrary, therefore the electric current producing class amplitude limit differential amplifier circuit 4B is adjusted, and puts eliminating class amplitude limit difference
Big circuit 4A produces the first order component in electric current.As it was previously stated, work as VIN-VREFM=ITAILBRB+3VTBe linear segment and one defeated
Enter pipe and enter the critical point of cut-off region.Therefore can be by adjusting reason ITAILBRBValue, the position of critical point is adjusted.In class
In amplitude limit differential amplifier circuit 4B, by using a big ITAILBRBValue, by the expanded range of linear segment to whole VIN
In the range of, say, that obtain the function of first order in the range of a total temperature, as shown in figure 23, shown in Figure 23 Yu Figure 24
Current value is overlapped, it is possible to export, in obtaining a medium temperature, the output current curve that electric current is smooth.
Now consider the situation of high-temperature part.When the temperature is low, now VINValue much larger than VREFL1。QC1Work in amplification
District, and QC2Cut-off.Now output electric current is respectively-ITAILC.Along with the rising of temperature, VINValue be gradually lowered, work as VINValue little
In VREFL1+ITAILCRC+3VTTime, now QC2Conducting, output electric current linearly changes with temperature, as shown in figure 25.
Low temperature part is slightly more complex.When temperature is higher, now VINValue much smaller than VREFH1。QD2Work in amplification
District, and QD1Cut-off.Now output electric current is ITAILD.Along with the reduction of temperature, VINValue gradually rise, work as VINValue be more than
VREFH1-ITAILDRD-3VTTime, now QD1Conducting, output electric current linearly changes with temperature, as shown in figure 26.So simulate three
The low temperature part of rank power function.
As it was previously stated, when center temperature drift is beyond the scope of 25-30 DEG C, now under low temperature state maximum with the highest
The difference of the extreme value of temperature can significantly strengthen, and now has to by entering low temperature part increase class amplitude limit differential amplifier circuit 4E
Row sum-equal matrix.As shown in figure 27, increase differential pair and can introduce a constant term deviation or referred to as zeroth order deviation, in order to this constant
Item makes up, and introduces QCPBranch road, tail current is set to identical and anti-phase, so with the tail current source amplitude of differential pair 4E
The zeroth order electric current payment that can be produced by class amplitude limit differential amplifier circuit 4E branch road, to realize calibrating zeroth order deviation.Thing
In reality, broader temperature compensation range and higher precision can be obtained by the method increasing difference channel with compensate electric current.
Final each road electric current is added, and obtains three rank power function current fitting curve as shown in figure 28.
Three, four, five rank function curve down to higher order can be obtained by the method for above-mentioned linear fit, and achieve one
The adjustment of individual broader temperature range.Owing to, in existing integrated circuit technology, the flicker noise of bipolar transistor is far below MOS
Type field effect transistor, and flicker noise is occupied an leading position at the low frequency end of circuit noise, therefore the use of bipolar transistor, have more
The advantage of high noise, to such an extent as to achieve bigger current margins, also make to use higher order function carry out temperature-compensating with
The way obtaining higher precision becomes a reality.