阅读说明：本技术 一种低温漂带隙基准电压源电路 (Low-temperature floating band gap reference voltage source circuit ) 是由 寿晓强 于 2019-09-27 设计创作，主要内容包括：本发明提供了一种低温漂带隙基准电压源电路,该低温漂带隙基准电压源电路包括电压输出电路、电压信号产生电路、及斩波放大器；其中：电压输出电路与电压信号产生电路电连接,为电压信号产生电路提供工作电压,电压信号产生电路为所述斩波放大器提供高频的差分信号；斩波放大器将该高频的差分信号及斩波放大器的失配电压放大后进行斩波调制处理,去除失配电压,为电压输出电路提供稳定的增益,以使电压输出电路输出带隙基准电压。本发明的低温漂带隙基准电源消除了放大器、PNP对的失配及其闪烁噪声的影响,在温度稳定性和消除低频噪声性能方面进行了改进。(The invention provides a low-temperature drift band gap reference voltage source circuit, which comprises a voltage output circuit, a voltage signal generating circuit and a chopper amplifier; wherein: the voltage output circuit is electrically connected with the voltage signal generating circuit and provides working voltage for the voltage signal generating circuit, and the voltage signal generating circuit provides high-frequency differential signals for the chopper amplifier; the chopper amplifier amplifies the high-frequency differential signal and the mismatch voltage of the chopper amplifier and then performs chopper modulation processing to remove the mismatch voltage and provide stable gain for the voltage output circuit so that the voltage output circuit outputs band-gap reference voltage. The low-temperature floating band-gap reference power supply eliminates the mismatch of an amplifier and a PNP pair and the influence of flicker noise thereof, and improves the temperature stability and the performance of eliminating low-frequency noise.)

1. A low-temperature floating band gap reference voltage source circuit is characterized by comprising a voltage output circuit, a voltage signal generating circuit and a chopper amplifier; wherein:

the voltage output circuit is electrically connected with the voltage signal generating circuit and provides working voltage for the voltage signal generating circuit, and the voltage signal generating circuit provides high-frequency differential signals for the chopper amplifier; and the chopper amplifier amplifies the high-frequency differential signal and the mismatch voltage of the chopper amplifier and then performs chopper modulation processing to remove the mismatch voltage and provide stable gain for the voltage output circuit so that the voltage output circuit outputs band-gap reference voltage.

2. The low-temperature floating bandgap reference voltage source circuit according to claim 1, wherein said voltage signal generating circuit comprises a modulation switch unit, a first resistor circuit, a second resistor circuit, a transistor Q5 and a transistor Q6; the first resistor circuit is electrically connected with the second resistor circuit, a first common end of the first resistor circuit, which is electrically connected with the second resistor circuit, is electrically connected with an emitter of the triode Q5, a second common end of the first resistor circuit, which is electrically connected with the second resistor circuit, is electrically connected with an emitter of the triode Q6, and a base and a collector of the triode Q5 are electrically connected with the ground; the base electrode of the triode Q6 and the collector electrode thereof are electrically connected to the ground; the first resistance circuit is electrically connected to one switch of the modulation switch unit, and the second resistance circuit is electrically connected to the other switch of the modulation switch unit.

3. The low temperature floating bandgap reference voltage source circuit according to claim 2, wherein said first resistor circuit comprises resistors R2, R7, R4; the second resistor circuit comprises resistors R1, R6, R5; a first end of the resistor R2 is electrically connected with a first end of the resistor R1, and an electrically connected end point of the resistor R2 is used as a first common end point of the first resistor circuit and the second resistor circuit; a second end of the resistor R2 is electrically connected with a first end of the resistor R7, and a second end of the resistor R7 is electrically connected with a first end of the resistor R4; a second terminal of the resistor R4 is electrically connected to a second terminal of the resistor R5, and the electrically connected terminal thereof is used as a second common terminal of the first resistor and the second resistor circuit; a second end of the resistor R1 is electrically connected with a first end of the resistor R6, and a second end of the resistor R6 is electrically connected with a first end of the resistor R5; a second terminal of the resistor R2 is electrically connected with a second terminal of the switch S5 of the modulation switch unit, and a second terminal of the resistor R6 is electrically connected with a second terminal of the switch S6 of the modulation switch unit; the first end of the switch S5 is electrically connected with the first end of the switch S6 and then electrically connected with the output end of the voltage output circuit; a second end of the resistor R1 is electrically connected with a second input end of the chopper amplifier, and a second end of the resistor R7 is electrically connected with a first input end of the chopper amplifier; and: r1 ═ R4; r7 ═ R6; r2 ═ R5; r7 ═ N × R2; the emitter area ratio of the transistor Q5 to the transistor Q6 is 1: 1.

4. The low temperature floating bandgap reference voltage source circuit according to claim 1, wherein said voltage output circuit comprises: an NMOS transistor M1 and a resistor R3; the grid electrode of the NMOS tube M1 is electrically connected with the output end of the chopper amplifier, the drain electrode of the NMOS tube M1 is electrically connected with an external power supply, the source electrode of the NMOS tube M1 is electrically connected with the resistor R3, and the source electrode of the NMOS tube M1 is used as the output end of the low-temperature floating band-gap reference voltage source circuit to output band-gap reference voltage.

5. The low temperature floating bandgap reference voltage source circuit according to claim 1, wherein said voltage output circuit comprises: PMOS transistor M2 and resistor R3; the grid electrode of the PMOS tube M2 is electrically connected with the output end of the chopper amplifier, the source electrode of the PMOS tube M2 is electrically connected with an external power supply, the drain electrode of the PMOS tube M2 is electrically connected with the resistor R3, and the drain electrode of the PMOS tube is used as the output end of the low-temperature drift band-gap reference voltage source circuit to output band-gap reference voltage.

6. The low temperature floating bandgap reference voltage source circuit according to any of claims 1 to 5, wherein said chopper amplifier comprises: a differential amplifier U1, a chopper demodulation switch A1 and a low pass filter LPF1 which are electrically connected in sequence; wherein:

the voltage signal generating circuit outputs a high-frequency modulated differential signal Vin and mismatch voltage of the differential amplifier U1 which are superposed to be used as input of the differential amplifier U1, the differential amplifier U1 amplifies the high-frequency differential signal Vin and the mismatch voltage, the high-frequency amplified input signal is modulated to be low frequency through the chopper demodulation switch A1, the amplified mismatch voltage is modulated to be high frequency, and the modulated high-frequency mismatch voltage is filtered through the low-pass filter LPF1 to obtain output voltage without the mismatch voltage.

7. The low-temperature floating-band-gap reference voltage source circuit as claimed in claim 6, wherein the chopper amplifier further comprises another amplifier U2, the input terminal of the amplifier U2 is electrically connected with the output terminal of the low-pass filter LPF1, and the output terminal of the amplifier U2 is used as the output terminal of the chopper amplifier.

8. The low temperature floating bandgap reference voltage source circuit according to claim 6, wherein said chopper demodulation switch comprises: the circuit comprises two input ends in1 and in2, two output ends out1 and out2, and four branch switches S1-S4; wherein:

when the clock signal is low, the first branch switch S1 and the fourth branch switch S4 are closed; when the clock signal is high, the second branch switch S2 and the third branch switch S3 are closed; when the first branch switch S1 is closed, the first input terminal in1 is communicated with the second output terminal out 2; when the second branch switch S2 is closed, the first input terminal in1 is communicated with the first output terminal out 1; when the third branch switch S3 is closed, the second input terminal in2 is communicated with the second output terminal out 2; when the fourth branch switch S4 is closed, the second input terminal in2 is communicated with the first output terminal out 1.

9. The low temperature floating bandgap reference voltage source circuit according to claim 2, wherein said transistor Q5 is replaced by a diode D1, said transistor Q6 is replaced by a diode D2; the anode of the diode D1 is electrically connected with the common end of the resistors R1 and R2, and the cathode of the diode D1 is electrically connected to the ground; the anode of the diode D2 is electrically connected with the common end of the resistors R4 and R5, and the cathode of the diode D2 is electrically connected to the ground.

Technical Field

The invention relates to the technical field of electronics, in particular to a low-temperature floating band gap reference voltage source circuit.

Background

At present, a reference voltage source has been used as an indispensable basic module in a semiconductor integrated circuit, which is widely used in amplifiers, analog-to-digital converters, digital-to-analog converters, radio frequencies, sensors, and power management chips. The conventional reference voltage source comprises a voltage reference based on reverse breakdown characteristics of a zener diode, a voltage reference based on forward conduction characteristics of a PN junction, a band gap reference and other implementation modes, wherein the band gap reference has the advantages of simple structure, stable voltage and the like, so that the reference voltage source is widely applied.

With the development of semiconductor technology and portable electronic products, the demand for reference voltage sources with low power consumption and high power supply voltage range is greatly increased, which also leads to a great increase in the design requirements of bandgap references. The bandgap reference can generate a reference voltage having stable temperature characteristics regardless of a power supply voltage and a process. The stability of the bandgap reference has a direct and crucial influence on the generation of the internal power supply, the adjustment of the output voltage, etc. of the whole system. The bandgap reference voltage must be able to overcome manufacturing process variations, variations in the system internal supply voltage over the operating range, and the effects of ambient temperature. As the accuracy of the system increases, the requirements on the temperature, voltage and process stability of the reference also increase.

Fig. 2 shows a conventional bandgap reference voltage source, the accuracy of which is significantly affected by the accuracy of the bipolar transistor, the temperature characteristics, the triode mismatch and the low frequency noise (flicker noise). In addition, smaller chip packages also result in higher package stress, resulting in greater voltage temperature drift. Therefore, the conventional bandgap reference voltage source is difficult to meet the performance requirements of the present integrated circuit or chip.

Disclosure of Invention

In order to solve at least one of the above technical problems, the present invention provides a low temperature drift bandgap reference voltage source circuit, and specifically, the low temperature drift bandgap reference voltage source circuit provided by the present invention includes: the voltage output circuit, the voltage signal generating circuit and the chopper amplifier; the voltage output circuit is electrically connected with the voltage signal generating circuit, provides working voltage for the voltage signal generating circuit and can also provide amplification of a required temperature signal. The voltage signal generating circuit provides a high-frequency differential signal for the chopper amplifier; and the chopper amplifier amplifies the high-frequency differential signal and the mismatch voltage of the chopper amplifier and then performs chopper modulation processing to remove the mismatch voltage and provide stable gain for the voltage output circuit so that the voltage output circuit outputs band-gap reference voltage.

In one embodiment, the voltage output circuit includes: an NMOS transistor M1 and a resistor R3; the grid electrode of the NMOS tube M1 is electrically connected with the output end of the chopper amplifier, the drain electrode of the NMOS tube M1 is electrically connected with an external power supply, the source electrode of the NMOS tube M1 is electrically connected with the resistor R3, and the source electrode of the NMOS tube M1 is used as the output end of the low-temperature floating band-gap reference voltage source circuit to output band-gap reference voltage.

Of course, the NMOS transistor in the above embodiment may also be replaced by a PMOS transistor, and specifically, the voltage output circuit includes: PMOS transistor M2 and resistor R3; the grid electrode of the PMOS tube M2 is electrically connected with the output end of the chopper amplifier, the source electrode of the PMOS tube M2 is electrically connected with an external power supply, the drain electrode of the PMOS tube M2 is electrically connected with the resistor R3, and the drain electrode of the PMOS tube is used as the output end of the low-temperature drift band-gap reference voltage source circuit to output band-gap reference voltage.

In one embodiment, the voltage signal generating circuit includes a modulation switch unit, a first resistor circuit, a second resistor circuit, a transistor Q5, and a transistor Q6; the first resistor circuit is electrically connected with the second resistor circuit, a first common end of the first resistor circuit, which is electrically connected with the second resistor circuit, is electrically connected with an emitter of the triode Q5, a second common end of the first resistor circuit, which is electrically connected with the second resistor circuit, is electrically connected with an emitter of the triode Q6, and a base and a collector of the triode Q5 are electrically connected with the ground; the base electrode of the triode Q6 and the collector electrode thereof are electrically connected to the ground; the first resistance circuit is electrically connected to one switch of the modulation switch unit, and the second resistance circuit is electrically connected to the other switch of the modulation switch unit.

In one embodiment, the first resistor circuit includes resistors R2, R7, R4; the second resistor circuit comprises resistors R1, R6, R5; a first end of the resistor R2 is electrically connected with a first end of the resistor R1, and an electrically connected end point of the resistor R2 is used as a first common end point of the first resistor circuit and the second resistor circuit; a second end of the resistor R2 is electrically connected with a first end of the resistor R7, and a second end of the resistor R7 is electrically connected with a first end of the resistor R4; a second terminal of the resistor R4 is electrically connected to a second terminal of the resistor R5, and the electrically connected terminal thereof is used as a second common terminal of the first resistor and the second resistor circuit; a second end of the resistor R1 is electrically connected with a first end of the resistor R6, and a second end of the resistor R6 is electrically connected with a first end of the resistor R5; a second terminal of the resistor R2 is electrically connected with a second terminal of the switch S5 of the modulation switch unit, and a second terminal of the resistor R6 is electrically connected with a second terminal of the switch S6 of the modulation switch unit; the first end of the switch S5 is electrically connected with the first end of the switch S6 and then electrically connected with the output end of the voltage output circuit; a second end of the resistor R1 is electrically connected with a second input end of the chopper amplifier, and a second end of the resistor R7 is electrically connected with a first input end of the chopper amplifier; and: r1 ═ R4; r7 ═ R6; r2 ═ R5; r7 ═ N × R2; the emitter area ratio of the transistor Q5 to the transistor Q6 is 1: 1.

In one embodiment, the chopper amplifier includes: a differential amplifier U1, a chopper demodulation switch A1 and a low pass filter LPF1 which are electrically connected in sequence; wherein:

the voltage signal generating circuit outputs a high-frequency differential signal Vin modulated by the output of the voltage signal generating circuit and a mismatch voltage of the differential amplifier U1 which are superposed to be used as the input of the differential amplifier U1, the differential amplifier U1 amplifies the high-frequency differential signal Vin and the mismatch voltage, the chopper demodulation switch A1 modulates the high-frequency amplified input signal to a low frequency, the amplified mismatch voltage is modulated to a high frequency, and the low-pass filter LPF1 filters the modulated high-frequency mismatch voltage to obtain an output voltage without the mismatch voltage.

In one embodiment, the chopper amplifier further comprises another amplifier U2, the input of the amplifier U2 being electrically connected to the output of the low pass filter LPF1, and the output of the amplifier U2 serving as the output of the chopper amplifier.

In one embodiment, the chopper demodulation switch comprises: two input terminals in1, in2, two output terminals out1, out2, and four branch switches S1 to S4. When the clock signal is low, the first branch switch S1 and the fourth branch switch S4 are closed; when the clock signal is high, the second branch switch S2 and the third branch switch S3 are closed; when the first branch switch S1 is closed, the first input terminal in1 is communicated with the second output terminal out 2; when the second branch switch S2 is closed, the first input terminal in1 is communicated with the first output terminal out 1; when the third branch switch S3 is closed, the second input terminal in2 is communicated with the second output terminal out 2; when the fourth branch switch S4 is closed, the second input terminal in2 is communicated with the first output terminal out 1.

In one embodiment, the transistor Q5 is replaced with a diode D1, the transistor Q6 is replaced with a diode D2; the anode of the diode D1 is electrically connected with the common end of the resistors R1 and R2, and the cathode of the diode D1 is electrically connected to the ground; the anode of the diode D2 is electrically connected with the common end of the resistors R4 and R5, and the cathode of the diode D2 is electrically connected to the ground.

The invention at least comprises the following technical effects:

(1) in the band-gap reference voltage source, the voltage signal generating circuit provides a high-frequency differential signal for the chopper amplifier, the differential signal consists of two voltage signals with the same amplitude and opposite polarities, the high-frequency differential signal is input to the input end of the chopper amplifier, and the high-frequency differential signal is changed into high frequency because the differential signal is modulated in the voltage signal generating circuit; the high-frequency differential signal is superposed with the low-frequency mismatch voltage of the chopper amplifier and then input to the chopper amplifier; the chopper amplifier performs chopping amplification on the input signal superimposed with the low-frequency mismatch voltage of the chopper amplifier, so that the mismatch voltage and noise of the voltage signal generation circuit are removed, and stable gain is output to the voltage output circuit, so that the voltage output circuit can output band-gap reference voltage according to the voltage signal fed back by the chopper amplifier.

(2) In a traditional band-gap reference voltage source, the ratio of the emitter areas of two triodes is 1: and N, the temperature characteristic of the triode is not high, the triode is easily influenced by temperature, and most importantly, the triode with a large emitter area is more easily influenced by stress, so that worse voltage temperature drift is caused. The band-gap reference voltage source adopts two sets of resistors with better temperature characteristics and precision, the area ratio of the emitting electrodes of the two triodes is 1:1, the influence caused by stress is eliminated, the input voltage signal of the first input end and the voltage signal of the second input end of the chopper amplifier can be input in an interchangeable way by reasonably setting the resistance value of the resistor in each set of resistors, the influence of PNP mismatch and flicker noise of the PNP mismatch and the flicker noise of the PNP mismatch are eliminated, and the influence of the mismatch voltage and the flicker noise of the amplifier is eliminated by adopting the chopper amplifier. Compared with the traditional band-gap reference voltage source, the band-gap reference voltage source circuit is greatly improved in temperature stability and low-frequency noise.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, it is obvious that the drawings in the following description are only some embodiments described in the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a block diagram of a low temperature floating bandgap reference voltage source circuit according to one embodiment of the present disclosure;

FIG. 2 is a prior art bandgap reference voltage source;

FIG. 3 is a block diagram of another embodiment of the low temperature floating bandgap reference voltage source circuit of the present invention;

FIG. 4 is a block diagram of another embodiment of the low temperature floating bandgap reference voltage source circuit of the present invention;

FIG. 5 is a circuit diagram of a voltage signal generating circuit of the low temperature drift bandgap reference voltage source circuit of the present invention;

FIG. 6 is a circuit diagram of another embodiment of a low temperature drift bandgap reference voltage source circuit of the present invention;

fig. 7 is a schematic diagram of a chopper demodulation switch structure.

The reference numbers illustrate:

10 voltage output circuit;

20 voltage signal generating circuit;

30 chopper amplifiers;

21 modulating the switching unit;

22 a first resistance circuit;

23 a second resistor circuit;

m1, Q1, Q2, Q5 and Q6 triodes

U1 differential amplifier (double input and double output)

U2 amplifier (double input single output)

A1 chopper demodulation switch

LPF1 low pass filter

Detailed Description

In order to make those skilled in the art better understand the technical solution of the present invention, the technical solution in the embodiment of the present invention will be clearly and completely described below with reference to the drawings in the embodiment of the present invention, and it is obvious that the described embodiment is only a part of the embodiment of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It will be understood that when an element is referred to as being "coupled" to another element, it can be directly coupled to the other element or intervening elements may also be present.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

An embodiment of the present invention provides a low-temperature floating bandgap reference voltage source circuit, as shown in fig. 1, including: a voltage output circuit 10, a voltage signal generation circuit 20, and a chopper amplifier 30; the voltage output circuit 10 is electrically connected to the voltage signal generating circuit 20, and provides a working voltage for the voltage signal generating circuit 20, and the voltage signal generating circuit 20 provides a differential signal for the chopper amplifier 30; the chopper amplifier 30 amplifies the high-frequency differential signal and the mismatch voltage of the chopper amplifier 30, and then performs chopper modulation processing to remove the mismatch voltage and provide stable gain for the voltage output circuit 10, so that the voltage output circuit outputs the bandgap reference voltage.

In the prior art, the basic topology of the reference voltage source is shown in fig. 2, where U2 is an amplifier and Q1, Q2 are diodes or transistors with their bases connected to their collectors. It can be easily seen that:

I_D1＝I_D2＝I_D (1)

V_REF＝V_BE2+I_D·(R₂+2R₃) (4)

where K is the Boltzmann constant, T is the absolute temperature, and q is the electronic charge. From (1) - - (4), we obtained:

note V_BE2Has a negative temperature coefficient, I_DProportional To Absolute Temperature (PTAT). By appropriate selection of N, R₁、R₂And R₃Value of V can be ensured_REFAnd remains constant throughout the temperature range. Of course, this is ideal, however, in practical applications, the bandgap reference voltage source shown in fig. 1 is prone to voltage temperature drift with increasing temperature, resulting in V_REFThe main errors of the drift include the input mismatch voltage of the amplifier, the emitter area ratio of 1: N and the resistance ratio R of the transistors Q1 and Q2₁:R₂:R₃。

The resistance performance is less influenced by temperature, so that the resistance ratio is easier to control, and the triode and the amplifier are limited by precision and are greatly influenced by the temperature, so that on one hand, the amplifier in the circuit can generate mismatch voltage; on the other hand, the emitter area ratio of the transistors Q1 and Q2 is 1: n, wherein N also has errors, particularly, smaller packaging can cause higher packaging stress, thereby causing the area of an emitter of the triode to be influenced, therefore, the area ratio 1: N can be caused to change, thereby causing great influence on the precision of the whole system, mismatch of the triode and the amplifier and flicker noise generated by the mismatch affect the output voltage V of the band-gap reference source_REF。

In the present invention, the voltage signal generating circuit generates a differential signal, i.e., a signal difference between the first voltage signal and the second voltage signal. The first voltage signal and the second voltage signal are input to the first input end and the second input end of the chopper amplifier, so that the mismatch influence of the voltage signal generating circuit is solved. The first voltage signal and the second voltage signal have the same amplitude and opposite polarity, and then the first voltage signal and the second voltage signal are input to two input ends of the chopper amplifier, so that a differential signal is provided for the chopper amplifier. Specifically, the voltage signal generating circuit can also switch the switch of the voltage signal generating circuit according to the high and low levels of the clock signal, so that the high-frequency differential signal is modulated and output, the mismatch influence of the voltage signal generating circuit is eliminated, the chopper amplifier performs chopping amplification processing on the input signal on which the mismatch voltage of the chopper amplifier is superposed, the mismatch voltage and noise of the voltage signal generating circuit are removed, stable gain is output to the voltage output circuit, and the voltage output circuit can output the band-gap reference voltage according to the voltage signal (gain) fed back by the chopper amplifier.

In another embodiment of the present invention, as shown in fig. 3, on the basis of the above-mentioned low temperature-drift bandgap reference voltage source circuit embodiment, the voltage output circuit 10 includes: PMOS transistor M2 and resistor R3; the grid electrode of the PMOS tube M2 is electrically connected with the output end of the chopper amplifier, the source electrode of the PMOS tube M2 is electrically connected with an external power supply, the drain electrode of the PMOS tube M2 is electrically connected with the resistor R3, and the drain electrode of the PMOS tube is used as the output end of the low-temperature drift band-gap reference voltage source circuit to output band-gap reference voltage.

Of course, the PMOS transistor in the above embodiment may also be replaced by an NMOS transistor, specifically, another implementation manner of the voltage output circuit is implemented by using an NMOS transistor M2 and a resistor R3, and specifically, as shown in fig. 4, the voltage output circuit 10 includes: an NMOS transistor M1 and a resistor R3; the grid electrode of the NMOS tube M1 is electrically connected with the output end of the chopper amplifier 30, the drain electrode of the NMOS tube M1 is electrically connected with an external power supply VDD, the source electrode of the NMOS tube M1 is electrically connected with the resistor R3, and the source electrode of the NMOS tube M1 is used as the output end of the low-temperature drift band-gap reference voltage source circuit to output band-gap reference voltage V_REF。

In the voltage output circuit 10, the chopper amplifier 30 inputs the amplified error voltage to the gate of the NMOS transistor M1, the drain of the NMOS transistor M1 is connected to an external power supply, and the voltage output from the source of the NMOS transistor M1 is very stable based on the negative feedback principle and can be used as a bandgap reference voltage.

In any of the above embodiments, the chopper amplifier 30 includes: a differential amplifier U1, a chopper demodulation switch A1 and a low pass filter LPF1 which are electrically connected in sequence; wherein:

the differential signal Vin (not shown) output by the voltage signal generating circuit 20 is superimposed with the mismatch voltage Vos (not shown) of the differential amplifier U1 to be used as the input of the differential amplifier U1, the differential amplifier U1 amplifies the differential signal Vin and the mismatch voltage Vos, the amplified input signal is modulated to a low frequency by the chopper demodulation switch a1, the amplified mismatch voltage is modulated to a high frequency, and the modulated high frequency mismatch voltage is filtered by the low pass filter LPF1 to obtain an output voltage without mismatch voltage.

Specifically, in the voltage signal generating circuit 20, the high-frequency differential signal generated by the modulation switch unit 21 is input to the first input terminal and the second input terminal of the differential amplifier U1 through switching modulation of the modulation switch unit 21, so as to eliminate the mismatch voltage of the voltage signal generating circuit 20, after the high-frequency input signal Vin and the low-frequency mismatch voltage Vos (of the differential amplifier) are amplified by the differential amplifier U1, the high-frequency amplified input signal Vin is modulated to the low frequency through the chopper demodulation switch a1, the low-frequency mismatch voltage Vos is modulated to the high frequency, and finally, the modulated high-frequency mismatch voltage is filtered through the low-pass filter LPF1, so as to obtain the output voltage without the mismatch voltage.

In any of the above embodiments, the voltage signal generating circuit 20 includes a modulation switch unit 21, a first resistor circuit 22, a second resistor circuit 23, a transistor Q5, and a transistor Q6; the modulation switch unit at least comprises two switches: s5 and S6, a first end of the switch S5 is electrically connected to a first end of the switch S6 and then electrically connected to an output end of the voltage output circuit, the first resistor circuit 22 is electrically connected to the second resistor circuit 23, a first common end of the first resistor circuit 22 electrically connected to the second resistor circuit 23 is electrically connected to an emitter of the transistor Q5, a second common end of the first resistor circuit 22 electrically connected to the second resistor circuit 23 is electrically connected to an emitter of the transistor Q6, and a base and a collector of the transistor Q5 are electrically connected to ground; the base of the triode Q6 and the collector thereof are electrically connected to the ground; the first resistance circuit 22 is electrically connected to a second terminal of one switch S5 of the modulation switch unit 21, and the second resistance circuit 23 is electrically connected to a second terminal of the other switch S6 of the modulation switch unit 21.

The base and the collector of the transistor Q5 are electrically connected to ground, which may be the base and the collector of Q5 shorted and then directly grounded, or the base of Q5 electrically connected to the collector through a resistor or an electrical network and then grounded, but the invention is not limited thereto.

The voltage signal generating circuit 20 modulates the switching of the switch unit 21 so that it generates a high-frequency differential signal, specifically, when the clock signal is at a high level, the switch S5 is turned on; when the clock signal is at a low level, the switch S6 is turned on, and thus, the differential signal generated by the voltage signal generation circuit 20 is modulated so that a high-frequency differential signal is generated.

The voltage signal generating circuit is shown in fig. 5, wherein the first resistor circuit comprises resistors R2, R7 and R4; the second resistor circuit comprises resistors R1, R6 and R5; a first end of the resistor R2 is electrically connected with a first end of the resistor R1, and an electrically connected end point of the resistor R2 is used as a first common end point of the first resistor circuit and the second resistor circuit; a second end of the resistor R2 is electrically connected with a first end of the resistor R7, and a second end of the resistor R7 is electrically connected with a first end of the resistor R4; a second terminal of the resistor R4 is electrically connected to a second terminal of the resistor R5, and the electrically connected terminal thereof is used as a second common terminal of the first resistor and the second resistor circuit; a second end of the resistor R1 is electrically connected with a first end of the resistor R6, and a second end of the resistor R6 is electrically connected with a first end of the resistor R5; a second terminal of the resistor R2 is electrically connected with a second terminal of the switch S5 of the modulation switch unit, and a second terminal of the resistor R6 is electrically connected with a second terminal of the switch S6 of the modulation switch unit; the first end of the switch S5 is electrically connected with the first end of the switch S6 and then electrically connected with the output end of the voltage output circuit; a second end of the resistor R1 is electrically connected with a second input end of the chopper amplifier, and a second end of the resistor R7 is electrically connected with a first input end of the chopper amplifier; and: r1 ═ R4; r7 ═ R6; r2 ═ R5; r7 ═ N × R2; the emitter area ratio of the transistor Q5 to the transistor Q6 is 1: 1.

In the conventional low-temperature-drift bandgap reference voltage source circuit shown in fig. 1, the emitter area ratio of the transistor Q2 to the transistor Q1 is 1: N, whereas in the present invention, R2: R7 is 1: N, and R5: R6 is 1: N; it is well known that the temperature characteristic and stability of the resistor is much higher than that of the transistor, and in particular, a smaller package of the transistor results in higher package stress, so that N in the ratio varies greatly, and PNP mismatch also has an effect on the overall system because it varies under stress. However, the temperature characteristic and stability of the resistor are high, for example, the precision of the precision resistor can reach 0.1%, and the temperature coefficient can reach within 20 ppm/DEG C, which is sufficient for most applications. In the embodiment, the area ratio of the emitting electrodes of the triodes Q5 and Q6 is 1:1, so that the packaging stress of a chip is reduced, the two sets of resistance circuits are switched by adopting the modulation switch unit, so that a differential signal input to the chopper amplifier is modulated to high frequency, the PNP mismatch and the influence of flicker noise of the PNP mismatch are eliminated, and the mismatch voltage influence of the amplifier is eliminated by adopting the chopper amplifier.

Chopper amplifier, see fig. 6, comprising: the differential amplifier U1, the chopper demodulation switch A1, the low pass filter LPF1 and the amplifier U2 are electrically connected in sequence, the input end of the amplifier U2 is electrically connected with the output end of the low pass filter LPF1, and the output end of the amplifier U2 is used as the output end of the chopper amplifier.

Specifically, the amplifier U2 amplifies the voltage signal filtered by the low-pass filter, and outputs the amplified voltage signal as a chopper amplifier to provide a stable gain for the voltage output module.

The chopper demodulation switch, as shown in fig. 7, includes: the circuit comprises two input ends in1 and in2, two output ends out1 and out2, and four branch switches S1-S4; when the clock signal is at a low level, the first branch switch S1 and the fourth branch switch S4 are closed; when the clock signal is high, the second branch switch S2 and the third branch switch S3 are closed; when the first branch switch S1 is closed, the first input terminal in1 is communicated with the second output terminal out 2; when the second branch switch S2 is closed, the first input terminal in1 is communicated with the first output terminal out 1; when the third branch switch S3 is closed, the second input terminal in2 is communicated with the second output terminal out 2; when the fourth branch switch S4 is closed, the second input terminal in2 is communicated with the first output terminal out 1.

We next verify the advancement of the bandgap reference voltage source of the present invention in terms of temperature stability (low temperature drift) and low frequency noise.

Specifically, as shown in fig. 5, the low-frequency bandgap reference voltage source of the present embodiment simultaneously eliminates the influence of Vos and PNP of the amplifier on the mismatch and the flicker noise thereof. To simplify the analysis, we assume that the clock φ is biased high. The following equation holds true:

R₂·I₁+R₁·I₃＝N·R₂·I₂ (6)

[R₁+(N+1)R₂]·I₃＝R₂·I₁ (9)

V_REF＝V_BE5+R₂·I₁+R₃·(I₁+I₂) (10)

from (6) - (10), we derive:

note that equation (11) is similar to equation (5), except for the scalar resulting from the resistance ratio. Also, R3 may simply be adjusted to ensure VREF remains constant over the entire temperature range.

The amplifier input offset voltage Vos and the emitter area ratio of Q5/Q6, 1+ δ, are both temperature dependent.

The operation of the circuit of fig. 5 is described as follows:

when the clock signal φ is high, the switches S5/S2/S3 are closed, S6/S1/S4 are open, R2> > R1,

from the start (11),

when the clock signal φ is low, the switches S6/S1/S4 are closed, S5/S2/S3 are open,

we have:

since the dc component of the chopping effect is its time average, it is directly obtained after the first order taylor expansion:

equation (14) approximates equation (11) and the non-ideal terms of Vos and δ are cancelled out. Thus, the bandgap reference voltage source of fig. 4 is greatly improved in temperature stability and low frequency noise performance.

Of course, the transistors Q5 and Q6 in the present invention may also be implemented by using diodes, and specifically, in any of the above embodiments, the transistor Q5 is replaced by the diode D1, and the transistor Q6 is replaced by the diode D2; the anode of the diode D1 is electrically connected with the common end of the resistors R1 and R2, and the cathode of the diode D1 is electrically connected with the ground; the anode of the diode D2 is electrically connected with the common end of the resistors R4 and R5, and the cathode of the diode D2 is electrically connected to the ground.

It should be noted that, in the description of the present invention, the terms "first", "second", and the like are used for descriptive purposes only and for distinguishing similar objects, and no precedence between the two is considered as indicating or implying relative importance. In addition, in the description of the present invention, "a plurality" means two or more unless otherwise specified.

It is to be understood that the above description is intended to be illustrative, and not restrictive. Many embodiments and many applications other than the examples provided will be apparent to those of skill in the art upon reading the above description. The scope of the present teachings should, therefore, be determined not with reference to the above description, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. The disclosures of all articles and references, including patent applications and publications, are hereby incorporated by reference for all purposes. The omission in the foregoing claims of any aspect of subject matter that is disclosed herein is not intended to forego the subject matter and should not be construed as an admission that the applicant does not consider such subject matter to be part of the disclosed subject matter.