CN206712762U - A kind of RC relaxors - Google Patents

Abstract

The utility model discloses a kind of RC relaxors, including charge and discharge capacitance C1 and the Digital Logical Circuits that assigned frequency square-wave signal is exported according to charging and discharging currents on charge and discharge capacitance C1, it is characterised in that：Described relaxor also includes charging and discharging currents regulation circuit and voltage reference circuit, the voltage reference circuit connection charging and discharging currents regulation circuit, and the electric current of the charging and discharging currents regulation circuit output carries out discharge and recharge to charge and discharge capacitance C1.The advantages of the utility model is to adjust circuit by charging and discharging currents, in that context it may be convenient to passes through control signal TRIM2 [7:0] frequency of oscillator output square-wave signal is controlled, produces the square-wave signal of assigned frequency；Control signal TRIM1 [7 can be passed through simultaneously:0], SETP, SETN reasonable disposition, influence of the temperature change to charging and discharging currents is eliminated, obtains assigned frequency square-wave signal independent of temperature variations.

Description

A kind of RC relaxors

Technical field

The utility model belongs to pierce circuit field, more particularly to a kind of to have and be automatically adjusted according to temperature change, Charging and discharging currents are kept stably to export the RC relaxors of assigned frequency.

Background technology

The classification of oscillator has many kinds, and one kind is that waveform is different according to caused by oscillator, is generally divided into sine Wave oscillator and relaxor, wherein, the output waveform of relaxor is rectangle square wave.And the circuit according to oscillator is real Existing mode is classified, and it is to realize that referred to as RC oscillator, also referred to as RC shake using resistor capacitor circuit to have a kind of circuit realiration Swing device.

In the electronic technology of early stage, RC oscillators are realized using the charge-discharge circuit of resistance and electric capacity.And In modern integrated circuits, resistance is usually substituted using current source.The circuits of traditional RC relaxors as shown in figure 1, its Circuit structure is mainly by constant current source (I1, I2), charge and discharge capacitance C, analog comparator (COMP1, COMP2), rest-set flip-flop Deng composition.Its operation principle is exactly to carry out discharge and recharge to electric capacity C using constant current, so as to produce impulse waveform.Shaken in relaxation Swing in device, the voltage VC at electric capacity C both ends compared with the reference voltage VH and VL of comparator COMP1 and COMP2 input, when During higher than reference voltage VH or less than reference voltage VL, the output state flip of comparator, finally in the output of rest-set flip-flop Q and QB is held to send out the rectangle square-wave signal of certain frequency.In the case where charging current is constant, electric capacity C both end voltages and charge and discharge The time linear approximate relationship of electricity, therefore, the time of capacitor charge and discharge can be changed by the setting to charging current, so as to Change pulsewidth and the cycle of impulse waveform.

RC relaxors it is relatively simple for structure, required power consumption is also smaller, and cost is relatively low, and frequency is easy to adjust, easily In being integrated into standard CMOS process integrated circuit, using very extensive.But because semiconductor technology is become by supply voltage Change and the influence of temperature change, the precision of RC relaxor output frequencies can also produce larger deviation, can not meet system Required precision.If not using inner, constant electric current, but external precision resister is used, then it is higher can to obtain precision Frequency of oscillation, still, so that the complexity of system can be increased, it can also increase area and cost.The relaxation of prior art In pierce circuit design, the frequency of outputting oscillation signal can be adjusted by the way of internal resistance electric capacity is adjusted, But the change of the change and temperature for supply voltage, regulation that still can not be automatic accurate is to stablize output frequency.

The content of the invention

The utility model is intended at least solve one of technical problem present in prior art.Therefore, the utility model carries For a kind of RC relaxors, it is therefore an objective to improve the stability of relaxor output square-wave signal frequency, control can be passed through Signal, control oscillator export square-wave signal frequency, produce the square-wave signal of assigned frequency；It can be believed simultaneously by other controls Number reasonable disposition, eliminate influence of the temperature change to charging and discharging currents, obtain assigned frequency side independent of temperature variations Ripple signal.

To achieve these goals, the technical scheme that the utility model is taken is：A kind of RC relaxors, including charge and discharge Electric capacity C1 and the Digital Logical Circuits that assigned frequency square-wave signal is exported according to charging and discharging currents on charge and discharge capacitance C1, its It is characterised by：Described relaxor also includes charging and discharging currents regulation circuit and voltage reference circuit, the voltage reference Circuit connection charging and discharging currents regulation circuit, the electric current of the charging and discharging currents regulation circuit output are carried out to charge and discharge capacitance C1 Discharge and recharge.

Charging and discharging currents regulation circuit include semifixed resistor R3, semifixed resistor R4, amplifier, transistor M4, M5, M6, M7, M8, M9, M10, M11, M12, M13, M14, M15 and M18, the reference voltage signal of the voltage reference circuit output VREF is input to the negative input end of amplifier, the output end connection transistor M12 of amplifier grid, transistor M12 source electrode The positive input terminal of amplifier and semifixed resistor R4 one end, semifixed resistor R4 other end ground connection, semifixed resistor R4 are connected respectively Control signal input control signal TRIM2 [7:0] to adjust semifixed resistor R4 resistance, transistor M12 drain electrode connects Transistor M11 drain electrode, transistor M11 source electrode connection power vd D, transistor M11 grid connect transistor M11's respectively The grid of drain electrode, transistor M13 grid and transistor M15, transistor M13 source electrode, M15 source electrode are all connected with power vd D, Transistor M13 drain electrode connects transistor M8 drain electrode, transistor M9 drain electrode, transistor M14 drain electrode, transistor respectively M14 grid connection transistor M18 grid, transistor M14 drain electrode are connected with its grid, transistor M18 and transistor M14 Source grounding；Transistor M8 source electrode connects with transistor M7 drain electrodes, transistor M7 source electrodes connection power vd D, transistor M7 gate input control signal SETP, transistor M8 grid connect transistor M6 grid and drain electrode, transistor M6 respectively Source electrode connection power vd D, transistor M6 drain electrode is connected with transistor M19 drain electrode, transistor M19 source ground, crystalline substance Body pipe M19 grid connects the grid of transistor M5 grid, transistor M5 drain electrode and transistor M9, transistor M9 sources respectively Pole is connected with transistor M10 drain electrode, transistor M10 source ground, transistor M10 gate input control signal SETN, Transistor M5 source ground, transistor M5 drain electrode are connected with M4 drain electrode, and transistor M4 source electrode passes through semifixed resistor R3 It is connected with power vd D, the control signal input control signal TRIM1 [7 of semifixed resistor:0], transistor M15 drain current Charging current is provided for electric capacity C1 through first switch, transistor M18 drain current provides electric discharge through second switch for electric capacity C1 Electric current.

Described semifixed resistor R3 and semifixed resistor R4 is solid relay.

Described Digital Logical Circuits includes comparator COMP1, comparator COMP2, rest-set flip-flop, not circuit, described The voltage at charge and discharge capacitance C1 both ends be separately input to comparator COMP1 positive input terminal and comparator COMP2 negative input End, comparator COMP1 negative input end and comparator COMP2 positive input terminal difference input reference voltage VH and reference voltage VL, comparator COMP1 output end and comparator COMP2 output end are separately input to the S pins and R pins of rest-set flip-flop, The Q output of rest-set flip-flop exports square-wave signal CLK by not circuit, and the Q output signal of rest-set flip-flop is input to second Switch, the QB output signals of rest-set flip-flop are connected with first switch.

The first switch, second switch are respectively transistor M16, transistor M17, and transistor M15 drain electrode connection is brilliant Body pipe M16 source electrode, transistor M16 grid and the QB pins of rest-set flip-flop connect, and transistor M16 drain electrode connects crystalline substance respectively Body pipe M17 drain electrode and charge and discharge capacitance C1 one end, charge and discharge capacitance C1 other end ground connection, transistor M17 source electrode connect Connect transistor M18 drain electrode, the Q pin output end of transistor M17 grid connection rest-set flip-flop.

Described voltage reference circuit includes transistor M1, transistor M2, transistor M3, simulation amplifier, bipolar transistor Pipe Q1, bipolar transistor Q2, bipolar transistor Q3, transistor M1, M2, M3 source electrode are all connected with power vd D, transistor M1 Drain electrode connect bipolar transistor Q1 emitter stage and the inverting input of simulation amplifier respectively, Q1 base stage and colelctor electrode connect Ground；Transistor M2 drain electrode is connected, by resistance R1's and bipolar transistor Q2 with simulating the in-phase input end of amplifier respectively Emitter stage connects, Q2 base stage and grounded collector；Transistor M3 drain electrode passes through resistance R2 connection bipolar transistors Q3's The base stage and grounded collector of emitter stage, bipolar transistor Q3, the output end for simulating amplifier connect transistor M1 grid respectively Pole, M2 grid, M3 grid, M4 grid, transistor M3 drain electrode output reference voltage VREF.

The advantages of the utility model is to adjust circuit by charging and discharging currents, in that context it may be convenient to passes through control signal TRIM2 [7:0] frequency of oscillator output square-wave signal is controlled, the square-wave signal of assigned frequency can be produced；It can be believed simultaneously by controlling Number TRIM1 [7:0], SETP, SETN reasonable disposition, influence of the temperature change to charging and discharging currents is eliminated, is obtained not by temperature Change the assigned frequency square-wave signal influenceed.

Brief description of the drawings

This specification includes the following drawings, and shown content is respectively：

Fig. 1 is the schematic diagram of RC relaxors in the prior art；

Fig. 2 is the circuit theory diagrams of RC relaxors of the present utility model.

Embodiment

Below against accompanying drawing, by the description to embodiment, specific embodiment of the present utility model is made further detailed Thin explanation, it is therefore an objective to help those skilled in the art have to design of the present utility model, technical scheme it is more complete, accurate and Deep understanding, and contribute to its implementation.

A kind of RC relaxors, including charge and discharge capacitance C1 and exported according to charging and discharging currents on charge and discharge capacitance C1 The Digital Logical Circuits of assigned frequency square-wave signal, relaxor also include charging and discharging currents regulation circuit and voltage reference electricity Road, voltage reference circuit connection charging and discharging currents regulation circuit, the electric current of charging and discharging currents regulation circuit output is to discharge and recharge electricity Hold C1 and carry out discharge and recharge.Voltage reference circuit adjusts circuit for discharge and recharge and provides reference voltage V REF, charging and discharging currents regulation electricity Road can adjust the size of charging and discharging currents, and the time that different charging and discharging currents sizes carries out discharge and recharge to electric capacity C1 is different, And then change the frequency of the square-wave signal of output.

The built-up circuit of oscillator is described further with reference to Fig. 2.

Charging and discharging currents regulation circuit include semifixed resistor R3, semifixed resistor R4, amplifier, transistor M4, M5, M6, M7, M8, M9, M10, M11, M12, M13, M14, M15 and M18, semifixed resistor R3 and semifixed resistor R4 are solid relay.Voltage The reference voltage signal VREF of reference circuit output is input to the inverting input of amplifier, the output end connection crystal of amplifier Pipe M12 grid, transistor M12 source electrode connect the in-phase input end of amplifier and semifixed resistor R4 one end respectively, fine setting Resistance R4 other end ground connection, semifixed resistor R4 control signal input control signal TRIM2 [7:0] to adjust semifixed resistor R4 resistance, transistor M12 drain electrode connection transistor M11 drain electrode, transistor M11 source electrode connection power vd D, transistor M11 grid connects the grid of transistor M11 drain electrode, transistor M13 grid and transistor M15 respectively, transistor M13's Source electrode, M15 source electrode are all connected with power vd D, and transistor M13 drain electrode connects transistor M8 drain electrode, transistor M9 respectively Drain electrode, transistor M14 drain electrode, transistor M14 grid connection transistor M18 grid, transistor M14 drain electrode and its grid Pole connects, transistor M18 and transistor M14 source grounding；Transistor M8 source electrode connects with transistor M7 drain electrodes, crystal Pipe M7 source electrodes connect power vd D, transistor M7 gate input control signal SETP, and transistor M8 grid connects crystal respectively Pipe M6 grid and drain electrode, transistor M6 source electrode connection power vd D, transistor M6 drain electrode and transistor M19 drain electrode connect Connect, transistor M19 source ground, transistor M19 grid connect respectively transistor M5 grid, transistor M5 drain electrode and Transistor M9 grid, transistor M9 source electrodes are connected with transistor M10 drain electrode, transistor M10 source ground, transistor M10 gate input control signal SETN, transistor M5 source ground, transistor M5 drain electrode are connected with M4 drain electrode, brilliant Body pipe M4 source electrode is connected by semifixed resistor R3 with power vd D, the control signal input control signal TRIM1 of semifixed resistor [7:0], transistor M15 drain current provides charging current, transistor M18 drain electrode electricity through first switch M16 for electric capacity C1 Flow through second switch M17 and provide discharge current for electric capacity C1.

Digital Logical Circuits includes comparator COMP1, comparator COMP2, rest-set flip-flop, not circuit, charge and discharge capacitance The voltage at C1 both ends is separately input to comparator COMP1 positive input terminal and comparator COMP2 negative input end, comparator COMP1 negative input end and comparator COMP2 positive input terminal difference input reference voltage VH and reference voltage VL, comparator COMP1 output end and comparator COMP2 output end are separately input to the R leads ends S pins and R pins of rest-set flip-flop, RS The Q output of trigger exports square-wave signal CLK by not circuit, and the Q output signal of rest-set flip-flop is input to second and opened Close M17, the QB output signals of rest-set flip-flop are connected with first switch M16.

First switch, second switch are respectively transistor M16, transistor M17, and transistor M15 drain electrode connects transistor M16 source electrode, transistor M16 grid and the QB pins of rest-set flip-flop connect, and transistor M16 drain electrode connects transistor respectively M17 drain electrode and charge and discharge capacitance C1 one end, charge and discharge capacitance C1 other end ground connection, transistor M17 source electrode connection are brilliant Body pipe M18 drain electrode, the Q pin output end of transistor M17 grid connection rest-set flip-flop.

Voltage reference circuit includes transistor M1, transistor M2, transistor M3, simulation amplifier, bipolar transistor Q1, double Bipolar transistor Q2, bipolar transistor Q3, transistor M1, M2, M3 source electrode are all connected with power vd D, transistor M1 drain electrode Bipolar transistor Q1 emitter stage and the negative input end of amplifier, Q1 base stage and grounded collector are connected respectively；Transistor M2 drain electrode is connected with simulating the in-phase input end of amplifier, connected by resistance R1 and bipolar transistor Q2 emitter stage respectively Connect, Q2 base stage and grounded collector；Transistor M3 drain electrode passes through resistance R2 connection bipolar transistors Q3 emitter stage, double Bipolar transistor Q3 base stage and grounded collector, the output end for simulating amplifier connect transistor M1 grid, M2 grid respectively Pole, M3 grid, M4 grid, transistor M3 drain electrode output reference voltage VREF.

Charging current of the transistor M15 drain current as charging and discharging currents C1, transistor M18 drain current conduct Electric capacity C1 discharge current.Transistor M15 and transistor M11 composition mirror image circuits, transistor M15 drain current is by transistor M11 drain electrode mirror image obtains, and transistor M11 drain current is relevant with the input signal VREF of semifixed resistor R4 and amplifier, I.e. electric capacity C1 charging current is relevant with reference voltage V REF and semifixed resistor R4 that voltage reference circuit exports, and semifixed resistor is Solid relay, it inputs control signal TRIM2 [7:0] it is used for the size for controlling semifixed resistor R4, so as to adjust charging electricity Stream.

Transistor M18 drain current is obtained by transistor M14 drain current mirror image, transistor M14 drain current It is made up of three parts：Transistor M13 drain current, transistor M8 drain current, transistor M9 drain current, transistor M14 drain currents are subtracted transistor M9 drain current by transistor M13 drain current superposition transistor M8 drain current again. Transistor M13 drain current is obtained by transistor M11 drain current mirror image, in the case where charging current is constant, i.e. M11 The constant i.e. semifixed resistor R4 and reference voltage V REF of input of drain current it is constant, discharge current only with M8 drain current with And M9 drain current is related.When transistor M8 drain current increase, discharge current increase；When M9 drain current increases When, discharge current can be reduced.Transistor M8 and transistor M6 composition current mirror circuits, and transistor M7 is to transistor M8's Drain current compensates, therefore M8 drain currents and M6 drain and transistor M7 is related, M6 drain current by M5 with It is related to transistor M4 drain current after the current mirror circuit of M19 compositions, similarly M9 drain current and transistor M10 with And M4 drain currents are related, transistor M4 drain current is controlled by semifixed resistor R3, when semifixed resistor R3 increases, M4 electric currents Reduce.Therefore M8, M9 drain current are relevant with semifixed resistor R3, and M8 is also relevant with M7, when M7 input control signal When SETP is high level, transistor M7 is closed, and disconnects transistor M8 drain electrode compensation electric current, M9 is also related to M10, when M10's When input control signal SETN is low level, transistor M10 is closed, and disconnects M9 drain electrode compensation electric current.

Therefore, input control signal SETN, the semifixed resistor R3 of discharge current and M7 input control signal SETP, M10 Control signal TRIM1 [7:0] relevant, charging current is relevant with voltage reference signal VREF with semifixed resistor R4.

When needing to export the frequency of different frequency square wave or fine setting output square wave, TRIM2 [7 can be passed through:0] adjust Semifixed resistor R4 size is saved, so as to adjust the size of charging current, and then adjusts or finely tunes the frequency of output square wave, reach tune The purpose of perfect square ripple output frequency, increase the pierce circuit frequency tunability, when there is process deviation, can adjust output side Wave frequency rate is to assigned frequency.

When at normal temperatures, such as 25 DEG C, control signal STEN is arranged to low level, and control signal STEP is arranged to high level, Pass through TRIM2 [7:0] configuration adjustment charging current, so as to control the output frequency of oscillator so that oscillator output frequency Rate is consistent with design expected frequency.In temperature change, then need to adjust control signal SETN, SETP, TRIM1 [7 accordingly: 0] to produce the discharge current varied with temperature, so as to be influenceed caused by compensation temperature change, and then stable output signal Frequency.When actually using oscillator, as the output frequency of fruit chip raises with temperature and the change of positive temperature coefficient is presented, then The discharge current of one negative temperature coefficient of generation can be passed through, it is possible to pass through the reduction of discharge current, reduce electric capacity electric discharge speed Degree, offset the change of frequency of oscillation that the positive temperature coefficient of script circuit is brought.In temperature change, if output frequency is with temperature Raising if increase, STEN is now configured to high level, M10 conductings, M9 drain current is the electric current of positive temperature coefficient, So M14 drain current is the drain current that initial drain subtracts M9 so that discharge current with temperature raise and Reduce, frequency reduces；If output frequency is raised and reduced with temperature, STEP is now configured to low level, M7 conductings, M8 leakage Pole is also the electric current of positive temperature coefficient, and M8 electric current is added with M13 electric current, flows into M14, forms what is raised and increase with temperature Electric current is compensated, so as to increase discharge current, the final frequency rise for causing outputting oscillation signal.The temperature coefficient of discharge current, By control signal TRIM1 [7:0] control the size of semifixed resistor to be realized to control, pass through control signal TRIM1 [7:0], control Signal SETN, STEP control the size of the temperature coefficient of discharge current, and so as to realizing under temperature change, compensation electric current produces The discharge current varied with temperature, and then the purpose of the output frequency of stabilized oscillator.

Using the RC relaxors of foregoing circuit, its output frequency can be adjusted or finely tuned according to the demand of reality output Output frequency, its adjusting method are the size by adjusting semifixed resistor R4, can be according to control because R4 is solid relay Signal TRIM2 [7:0] big minor adjustment R4 size, realize that oscillator exports different frequencies.In real work, due to ring The change of square wave frequency is exported caused by the change of border temperature, can be by adjusting control signal SETN, SETP, TRIM1 [7:0] The characteristic for increasing or reducing to adjust discharge current with temperature, when temperature changes, compensation circuit produces putting with temperature increase When electric current or the discharge current reduced with temperature carry out compensation temperature change, the change of output frequency, so as to stable output square wave Frequency.

The utility model is exemplarily described above in association with accompanying drawing.Obviously, the utility model implements not Limited by aforesaid way.As long as employ the various unsubstantialities that methodology and technical scheme of the present utility model are carried out Improvement；Or it is not improved, above-mentioned design of the present utility model and technical scheme are directly applied into other occasions, at this Within the protection domain of utility model.

Claims (6)

1. a kind of RC relaxors, including charge and discharge capacitance C1 and referred to according to charging and discharging currents output on charge and discharge capacitance C1 Determine the Digital Logical Circuits of frequency square wave signal, it is characterised in that：Described relaxor also includes charging and discharging currents and adjusted Circuit and voltage reference circuit, the voltage reference circuit connection charging and discharging currents regulation circuit, the charging and discharging currents regulation The electric current of circuit output carries out discharge and recharge to charge and discharge capacitance C1.

A kind of 2. RC relaxors as claimed in claim 1, it is characterised in that：The charging and discharging currents regulation circuit includes Semifixed resistor R3, semifixed resistor R4, amplifier, transistor M4, M5, M6, M7, M8, M9, M10, M11, M12, M13, M14, M15 And M18, the reference voltage signal VREF of voltage reference circuit output are input to the negative input end of amplifier, amplifier it is defeated Go out end connection transistor M12 grid, transistor M12 source electrode connects the positive input terminal and semifixed resistor R4 of amplifier respectively One end, semifixed resistor R4 other end ground connection, semifixed resistor R4 control signal input control signal TRIM2 [7:0] with tune Save semifixed resistor R4 resistance, transistor M12 drain electrode connection transistor M11 drain electrode, transistor M11 source electrode connection power supply VDD, transistor M11 grid connect the grid of transistor M11 drain electrode, transistor M13 grid and transistor M15 respectively, Transistor M13 source electrode, M15 source electrode are all connected with power vd D, transistor M13 drain electrode connect respectively transistor M8 drain electrode, Transistor M9 drain electrode, transistor M14 drain electrode, transistor M14 grid connection transistor M18 grid, transistor M14's Drain electrode is connected with its grid, transistor M18 and transistor M14 source grounding；Transistor M8 source electrode leaks with transistor M7 Pole connects, and transistor M7 source electrodes connect power vd D, transistor M7 gate input control signal SETP, transistor M8 grid Transistor M6 grid and drain electrode, transistor M6 source electrode connection power vd D, transistor M6 drain electrode and transistor are connected respectively M19 drain electrode connection, transistor M19 source ground, transistor M19 grid connect transistor M5 grid, crystal respectively Pipe M5 drain electrode and transistor M9 grid, transistor M9 source electrodes are connected with transistor M10 drain electrode, transistor M10 source electrode Ground connection, transistor M10 gate input control signal SETN, transistor M5 source ground, transistor M5 drain electrode is with M4's Drain electrode connection, transistor M4 source electrode are connected by semifixed resistor R3 with power vd D, the control signal input control of semifixed resistor Signal TRIM1 [7 processed:0], transistor M15 drain current provides charging current, transistor M18 through first switch for electric capacity C1 Drain current provide discharge current through second switch for electric capacity C1.

A kind of 3. RC relaxors as claimed in claim 2, it is characterised in that：Described semifixed resistor R3 and semifixed resistor R4 is solid relay.

A kind of 4. RC relaxors as claimed in claim 2, it is characterised in that：Described Digital Logical Circuits includes comparing Device COMP1, comparator COMP2, rest-set flip-flop, not circuit, the voltage at described charge and discharge capacitance C1 both ends are separately input to Comparator COMP1 positive input terminal and comparator COMP2 negative input end, comparator COMP1 negative input end and comparator COMP2 positive input terminal difference input reference voltage VH and reference voltage VL, comparator COMP1 output end and comparator COMP2 output end is separately input to the S pins and R pins of rest-set flip-flop, and the Q output of rest-set flip-flop is defeated by not circuit Go out square-wave signal CLK, the Q output signal of rest-set flip-flop is input to the QB output signals and first of second switch, rest-set flip-flop Switch connection.

A kind of 5. RC relaxors as claimed in claim 4, it is characterised in that：The first switch, second switch difference For transistor M16, transistor M17, transistor M15 drain electrode connection transistor M16 source electrode, transistor M16 grid and RS The QB pins connection of trigger, transistor M16 drain electrode connect respectively transistor M17 drain electrode and charge and discharge capacitance C1 one End, charge and discharge capacitance C1 other end ground connection, transistor M17 source electrode connection transistor M18 drain electrode, transistor M17 grid Pole connects the Q pin output end of rest-set flip-flop.

A kind of 6. RC relaxors as claimed in claim 2, it is characterised in that：Described voltage reference circuit includes crystal Pipe M1, transistor M2, transistor M3, simulation amplifier, bipolar transistor Q1, bipolar transistor Q2, bipolar transistor Q3, Transistor M1, M2, M3 source electrode are all connected with power vd D, and transistor M1 drain electrode connects bipolar transistor Q1 transmitting respectively Pole and the inverting input of simulation amplifier, Q1 base stage and grounded collector；Transistor M2 drain electrode is respectively with simulating amplifier In-phase input end is connected, is connected by resistance R1 with bipolar transistor Q2 emitter stage, Q2 base stage and grounded collector；It is brilliant Body pipe M3 drain electrode passes through resistance R2 connection bipolar transistors Q3 emitter stage, bipolar transistor Q3 base stage and colelctor electrode Ground connection, the output end for simulating amplifier connect transistor M1 grid, M2 grid, M3 grid, M4 grid, transistor respectively M3 drain electrode output reference voltage VREF.