阅读说明：本技术 一种具有低温度系数的带隙基准电路 (Band gap reference circuit with low temperature coefficient ) 是由 王新胜 白春阳 王静 于 2021-07-05 设计创作，主要内容包括：本发明涉及一种具有低温度系数的带隙基准电路,其解决了如何改善Brokaw带隙基准电路的性能的技术问题,其在Brokaw带隙基准电路的基础上增加一个放大器从而形成闭环稳定基准电路输出电压。本发明广泛用于为集成电路提供参考电压。(The invention relates to a band-gap reference circuit with a low temperature coefficient, which solves the technical problem of how to improve the performance of a Brokaw band-gap reference circuit. The invention is widely used for providing reference voltage for integrated circuits.)

1. A band gap reference circuit with a low temperature coefficient comprises a fifteenth MOSFET, a third resistor, a fourth resistor, a first BJT transistor, a second resistor, a first resistor and a first amplifier, wherein the source electrode of the fifteenth MOSFET is connected with a power supply, one end of the third resistor is connected with the drain electrode of the fifteenth MOSFET, the other end of the third resistor is connected with the collector electrode of the first BJT transistor, one end of the fourth resistor is connected with the drain electrode of the fifteenth MOSFET, the other end of the fourth resistor is connected with the collector electrode of the second BJT transistor, the base electrode of the first BJT transistor is connected with the base electrode of the second BJT transistor, the emitter electrode of the first BJT transistor is grounded through the second resistor and the first resistor, the emitter electrode of the second BJT transistor is connected with a node between the second resistor and the first resistor, and a node between the third resistor and the collector electrode of the first BJT transistor is connected with the positive phase input end of the first amplifier, the band-gap reference circuit with the low temperature coefficient is characterized by further comprising a second amplifier, wherein the second amplifier is provided with a first positive phase input end, a second positive phase input end, an inverse phase input end and an output end, a node between a third resistor and the collector of the first BJT transistor is connected with the first positive phase input end, a node between the fourth resistor and the collector of the second BJT transistor is connected with the second positive phase input end, the inverse phase input end of the second amplifier is connected with the base of the second BJT transistor, and the grid of a fifteenth MOSFET is connected with the output end of the second amplifier.

2. The bandgap reference circuit with low temperature coefficient according to claim 1, wherein the second amplifier comprises a thirteenth MOSFET transistor, a fourteenth MOSFET transistor, a fifth BJT transistor, a fourth BJT transistor, a third BJT transistor, a sixth resistor, a fifth resistor and a twelfth MOSFET transistor, wherein the collector of the fifth BJT transistor and the collector of the fourth BJT transistor are connected together and then connected to the drain of the thirteenth MOSFET transistor, the emitter of the fifth BJT transistor and the emitter of the fourth BJT transistor are connected together and then connected to one end of the sixth resistor, the other end of the sixth resistor is connected to the drain of the twelfth MOSFET transistor, the emitter of the third BJT transistor is connected to the drain of the twelfth MOSFET transistor through the fifth resistor, the collector of the third BJT transistor is connected to the drain of the fourteenth BJT transistor, and the gate of the fourteenth MOSFET transistor is connected to the gate of the thirteenth MOSFET, the source electrode of the thirteenth MOSFET is connected with the power supply, the source electrode of the fourteenth MOSFET is connected with the power supply VDD, the grid electrode and the drain electrode of the thirteenth MOSFET are connected together, the source electrode of the twelfth MOSFET is grounded, the base electrode of the fifth BJT transistor is used as the first positive phase input end of the second amplifier, the base electrode of the fourth BJT transistor is used as the second positive phase input end, the base electrode of the third BJT transistor is used as the reverse phase input end, and the collector electrode of the third BJT transistor is used as the output end.

Technical Field

The invention relates to the technical field of band-gap reference circuits in integrated circuits, in particular to a band-gap reference circuit with a low temperature coefficient.

Background

The bandgap reference circuit is a crucial module in an integrated circuit, and can provide a reference voltage with small fluctuation variation due to temperature, power supply voltage and process for other circuit systems. The bandgap reference circuit is usually integrated in a digital-to-analog converter, an analog-to-digital converter, a low dropout regulator, etc. to provide a reference voltage for the digital-to-analog converter, the analog-to-digital converter, the low dropout regulator, etc.

Referring to the Brokaw bandgap reference circuit of fig. 1, the basic principle is to superimpose a voltage with positive temperature coefficient and a voltage with negative temperature coefficient in proper proportion to obtain a reference voltage with approximately zero temperature coefficient at the output of the reference circuit. Voltage V₊Having a positive temperature coefficient and a negative temperature coefficient, the voltage V-satisfies equation (1) by selecting appropriate weights β and α.

An output voltage with a zero temperature coefficient can be obtained, and the expression of the output voltage is shown in formula (2).

V_REF＝αV₊+βV_- (2)

CTAT voltage V_-Typically by the base-emitter voltage V of a Bipolar Junction Transistor (BJT)_BEProviding, a PTAT voltage V₊Base-emitter voltage V from two BJTs with different areas_BEDifference value Δ V of_BEAnd (4) generating.

Therefore, with the development of integrated circuit technology, how to improve the performance of the Brokaw bandgap reference circuit is a technical problem to be solved urgently by those skilled in the art.

Disclosure of Invention

The invention provides a bandgap reference circuit with a low temperature coefficient, aiming at solving the technical problem of improving the performance of the conventional Brokaw bandgap reference circuit.

The invention provides a band-gap reference circuit with a low temperature coefficient, which comprises a fifteenth MOSFET, a third resistor, a fourth resistor, a first BJT transistor, a second resistor, a first resistor and a first amplifier, wherein the source electrode of the fifteenth MOSFET is connected with a power supply, one end of the third resistor is connected with the drain electrode of the fifteenth MOSFET, the other end of the third resistor is connected with the collector electrode of the first BJT transistor, one end of the fourth resistor is connected with the drain electrode of the fifteenth MOSFET, the other end of the fourth resistor is connected with the collector electrode of the second BJT transistor, the base electrode of the first BJT transistor is connected with the base electrode of the second BJT transistor, the emitter electrode of the first BJT transistor is grounded through the second resistor and the first resistor, the emitter electrode of the second BJT transistor is connected with a node between the second resistor and the first resistor, and the node between the collector electrode of the third resistor and the first BJT transistor is connected with the positive phase input end of the first amplifier, the node between the fourth resistor and the collector of the second BJT transistor is connected with the inverting input end of the first amplifier, the output end of the first amplifier is connected with the base of the first BJT transistor, the band-gap reference circuit with the low temperature coefficient further comprises a second amplifier, the second amplifier is provided with a first positive phase input end, a second positive phase input end, an inverting input end and an output end, the node between the third resistor and the collector of the first BJT transistor is connected with the first positive phase input end, the node between the fourth resistor and the collector of the second BJT transistor is connected with the second positive phase input end, the inverting input end of the second amplifier is connected with the base of the second BJT transistor, and the grid of a fifteenth MOSFET is connected with the output end of the second amplifier.

Preferably, the second amplifier comprises a thirteenth MOSFET tube, a fourteenth MOSFET tube, a fifth BJT transistor, a fourth BJT transistor, a third BJT transistor, a sixth resistor, a fifth resistor and a twelfth MOSFET tube, wherein a collector of the fifth BJT transistor and a collector of the fourth BJT transistor are connected together and then connected to a drain of the thirteenth MOSFET tube, an emitter of the fifth BJT transistor and an emitter of the fourth BJT transistor are connected together and then connected to one end of the sixth resistor, the other end of the sixth resistor is connected to a drain of the twelfth MOSFET tube, an emitter of the third BJT transistor is connected to a drain of the twelfth MOSFET tube through the fifth resistor, a collector of the third BJT transistor is connected to a drain of the fourteenth MOSFET tube, a gate of the fourteenth MOSFET tube is connected to a gate of the thirteenth MOSFET tube, a source of the thirteenth MOSFET tube is connected to the power supply, a source of the fourteenth MOSFET tube is connected to the source VDD, and a gate and a drain of the thirteenth MOSFET tube are connected together, the source electrode of the twelfth MOSFET is grounded, the base electrode of the fifth BJT transistor is used as a first positive phase input end of the second amplifier, the base electrode of the fourth BJT transistor is used as a second positive phase input end, the base electrode of the third BJT transistor is used as an inverted phase input end, and the collector electrode of the third BJT transistor is used as an output end.

The invention has the advantages that the temperature coefficient of the conventional Brokaw band-gap reference circuit is optimized, the advantage of ultralow temperature coefficient is achieved, the noise performance is better, and the requirement of a high-precision circuit system on the reference circuit can be met.

Further features and aspects of the present invention will become apparent from the following description of specific embodiments with reference to the accompanying drawings.

Drawings

FIG. 1 is a circuit schematic of a Brokaw bandgap reference circuit;

FIG. 2 is a circuit diagram of a bandgap reference circuit of the present invention;

fig. 3 is a circuit diagram of the amplifier AMP 2;

fig. 4 is a circuit diagram of the amplifier AMP 1;

FIG. 5 is a graph showing simulation of temperature characteristics of a bandgap reference circuit according to the present invention;

FIG. 6 is a graph of a simulation of the linear adjustment rate of the bandgap reference circuit of the present invention;

FIG. 7 is a simulation diagram of the power supply rejection ratio of the bandgap reference circuit of the present invention;

fig. 8 is a graph of the output noise simulation of the bandgap reference circuit of the present invention.

The symbols in the drawings illustrate that:

M1-M15 are the first to the fifteenth MOSFET, R1-R9 are the first to the ninth resistor, Q1-Q7 are the first to the seventh BJT transistor, C1 is the capacitor, VDD is the power, VSS is the ground, V1 is the power supply_REFINN, INP1, INP2 are input terminals of a second amplifier AMP2, V is a reference circuit output voltage_OUTIs the output terminal of the second amplifier AMP2, INN1, INN2 is the input terminal of the first amplifier AMP1, V_BIAS1、V_BIAS2Is the bias voltage of the current mirror.

Detailed Description

The present invention will be described in further detail below with reference to specific embodiments thereof with reference to the attached drawings.

As shown in fig. 2, the bandgap reference circuit with low temperature coefficient of the present invention comprises a fifteenth MOSFET M15, a third resistor R3, a fourth resistor R4, a first BJT transistor Q1, a second BJT transistor Q2, the second resistor R2, the first resistor R1, the first amplifier AMP1, the second amplifier AMP2, the source of the fifteenth MOSFET M15 is connected with the power supply VDD, one end of the third resistor R3 is connected with the drain of the fifteenth MOSFET M15, the other end of the third resistor R3 is connected with the collector of the first BJT transistor Q1, one end of the fourth resistor R4 is connected with the drain of the fifteenth MOSFET, the other end of the fourth resistor R4 is connected with the collector of the second BJT transistor Q2, the base of the first BJT transistor Q1 is connected with the base of the second BJT transistor Q2, the emitter of the first BJT transistor Q1 is grounded through the second resistor R2 and the first resistor R1, and the emitter of the second BJT transistor Q2 is connected with the node between the second resistor R2 and the first resistor R1. A node a1 between the third resistor R3 and the collector of the first BJT transistor Q1 is connected to a non-inverting input terminal of the first amplifier AMP1, a node a2 between the fourth resistor R4 and the collector of the second BJT transistor Q2 is connected to an inverting input terminal of the first amplifier AMP1, and an output terminal of the first amplifier AMP1 is connected to a base of the first BJT transistor Q1. The gate of the fifteenth MOSFET M15 is connected to the output terminal of the second amplifier AMP 2.

The second amplifier AMP2, shown in FIG. 3, may be considered as a combination of two double-ended input single-ended output amplifiers having a common inverting input INN and an output V_OUTAnd a power supply VDD, a fifth resistor R5 and a sixth resistor R6 are added to an emitter of an input tube of the amplifier to improve the linearity of the amplifier, and the fifth resistor R5 and the sixth resistor R6 are negative feedback resistors. The second amplifier AMP2 includes a thirteenth MOSFET M13, a fourteenth MOSFET M14, a fifth BJT transistor Q5, a fourth BJT transistor Q4, a third BJT transistor Q3, a sixth resistor R6, a fifth resistor R5, a twelfth MOSFET M12, a collector of the fifth BJT transistor Q5 and a collector of the fourth BJT transistor Q4 are connected together and then connected to a drain of the thirteenth MOSFET M13, an emitter of the fifth BJT transistor Q5 and an emitter of the fourth BJT transistor Q4 are connected together and then connected to one end of the sixth resistor R6, the other end of the sixth resistor R6 is connected to a drain of the twelfth MOSFET M12, an emitter of the third BJT Q3 is connected to a drain of the twelfth MOSFET M12 through a fifth resistor R5, a collector of the third BJT Q3 is connected to a drain of the fourteenth MOSFET M14, a gate of the fourteenth MOSFET M14 is connected to a source of the thirteenth BJT M13, a source of the thirteenth BJT M13, the source of the fourteenth MOSFET M14 is connected to the power supply VDD, the gate and the drain of the thirteenth MOSFET M13 are connected together, the source of the twelfth MOSFET M12 is grounded, and the base of the fifth BJT transistor Q5 is used as the first non-inverting input IN of the second amplifier AMP2P1, the base of the fourth BJT transistor Q4 as the second non-inverting input INP2, the base of the third BJT transistor Q3 as the inverting input INN, and the collector of the third BJT transistor Q3 as the output V_OUTThe gate of the twelfth MOSFET M12 is connected to the control signal V_BIAS5. The drain of the twelfth MOSFET M12 is connected to the control signal PIBO 1. The second amplifier AMP2 is used for clamping the node potentials of the nodes A1 and A2 at V by using the characteristic that the input end is' virtual short_REFNearby, ensure BJT transistors Q1, Q2 work in the amplification region and form a feedback loop to stabilize the output voltage. The inverting input terminal INN is connected to the base of the second BJT transistor Q2, the first non-inverting input terminal INP1 is connected to the node A1 between the third resistor R3 and the collector of the first BJT transistor Q1, the second non-inverting input terminal INP2 is connected to the node A2 between the fourth resistor R4 and the collector of the second BJT transistor Q2, and the output terminal V is connected to the output terminal V_OUTIs connected with the gate of the fifteenth MOSFET M15.

The provision of the second amplifier AMP2 enables: on one hand, Q1 and Q2 can be arranged to work in an amplification region, and on the other hand, a closed-loop stable reference circuit output voltage is formed, so that the reference circuit has better stability.

As shown in fig. 4, the first amplifier AMP1 may specifically adopt a two-stage amplifier, where the first stage adopts a current mirror circuit composed of a first MOSFET M1 and a second MOSFET M2 as a load, and negative feedback resistors R7 and R8 are added to the source to reduce the influence of circuit mismatch and 1/f noise of M1 and M2; the second stage of the amplifier adopts a common source amplifier structure, so that the gain of the amplifier can be improved; r9 is zero setting resistance, and C1 is miller compensation capacitance, and the effect is to carry out frequency compensation to the amplifier, improves amplifier stability.

Due to the base-emitter voltage difference V of the BJT transistor_BEThe expression is formula (3).

The voltage difference across the second resistor R2 is expressed by equation (4).

With the first amplifier AMP1 "pseudo-short" characteristic, A is adjusted₁、A₂Two-node clamping, so that A in FIG. 2₁、A₂The node potentials are approximately equal due to the third resistor R₃And a fourth resistor R₄Are directly connected together, setting a third resistance R₃And a fourth resistor R₄The resistance is the same, then the first BJT transistor Q₁And a second BJT transistor Q₂The currents of the two branches are approximately equal. In addition, due to I_SIs in direct proportion to its area, Q₁And Q₂Is set to 72:9, corresponding to I_SThe ratio of R to R is also 72:9, and the formula (4) can be simplified to obtain R₂Voltage difference V of_R2See formula (5).

Therefore, the output end voltage V of the band gap reference circuit of the invention_REFIs the expression (6)

By regulating R₁And R₂Is such that the reference voltage V_REFA zero temperature coefficient is obtained at a certain temperature point.

The band gap reference circuit of the invention is simulated:

setting VDD power supply voltage as 5V DC voltage, and under TT process angle, performing DC scanning on simulation temperature of the reference circuit at-40 ℃ to 85 ℃, wherein V is_REFAs shown in FIG. 5, the output voltage V is within the temperature range of-40 deg.C to 85 deg.C_REFFluctuates in the range of 1.25312V to 1.25243V with an error of about 0.69mV, and the temperature coefficient calculated to work at a temperature in the range of-40 ℃ to 85 ℃ is 4.405ppm/℃。

Setting VDD power supply voltage to be 5V, simulation temperature to be 25 ℃, performing 3.6V-5.5V direct current scanning on input power supply voltage under TT process angle, and generating linear adjustment rate simulation graph of output voltage VREF as shown in figure 6, wherein V is_REFThe variation range is 1.253129V-1.253108V, the error is about 21 muV, and the linear adjustment rate is 11.7 muV/V.

The simulation temperature is set to be 25 ℃, the power supply voltage is 5V direct current voltage and 1V alternating current voltage is added, power supply rejection ratio simulation is carried out on the first-order band gap reference circuit under the TT process angle, and the simulation result is shown in figure 7. The power supply rejection ratio of the circuit at the low frequency of 1Hz is 89.12 dB; the power supply rejection ratio at 10kHz was 32.98 dB.

Setting the VDD power supply voltage as 5V direct current voltage, the simulation temperature as 25 ℃, performing noise simulation on the first-order band gap reference circuit under the TT process angle, setting the simulation frequency as 1 Hz-1 GHz, and setting the simulation result as shown in figure 8, wherein the circuit output noise at the low frequency of 1kHz is

The above description is only for the purpose of illustrating preferred embodiments of the present invention and is not to be construed as limiting the present invention, and it is apparent to those skilled in the art that various modifications and variations can be made in the present invention.