阅读说明：本技术 一种带隙基准电路 (Band gap reference circuit ) 是由 杨全 谷申 林立谨 于 2019-10-09 设计创作，主要内容包括：本发明公开了一种带隙基准电路,包含启动电路、带隙基准电压电路和输出电路；所述启动电路与所述带隙基准电压电路相连,用于向所述带隙基准电压电路提供启动所需的电压,所述带隙基准电压电路用于产生带隙基准电压,通过所述输出电路输出；所述启动电路由一个电容构成,一端连接于电源端,另一端连接于所述带隙基准电压电路。本发明带隙基准电路的启动电路由一个电容构成,利用了电容的电量/电压保持特性,结构简单,无需功耗又能可靠启动,保证带隙基准电路稳定输出。(The invention discloses a band-gap reference circuit, which comprises a starting circuit, a band-gap reference voltage circuit and an output circuit, wherein the starting circuit is connected with the band-gap reference voltage circuit; the starting circuit is connected with the band-gap reference voltage circuit and used for providing voltage required by starting for the band-gap reference voltage circuit, and the band-gap reference voltage circuit is used for generating band-gap reference voltage and outputting the band-gap reference voltage through the output circuit; the starting circuit is composed of a capacitor, one end of the capacitor is connected to a power supply end, and the other end of the capacitor is connected to the band-gap reference voltage circuit. The starting circuit of the band-gap reference circuit is composed of a capacitor, utilizes the electric quantity/voltage retention characteristic of the capacitor, has a simple structure, can be reliably started without power consumption, and ensures the stable output of the band-gap reference circuit.)

1. A band-gap reference circuit is characterized by comprising a starting circuit, a band-gap reference voltage circuit and an output circuit; the starting circuit is connected with the band-gap reference voltage circuit and used for providing voltage required by starting for the band-gap reference voltage circuit, and the band-gap reference voltage circuit is used for generating band-gap reference voltage and outputting the band-gap reference voltage through the output circuit; the starting circuit is composed of a capacitor, one end of the capacitor is connected to a power supply end, and the other end of the capacitor is connected to the band-gap reference voltage circuit.

2. The bandgap reference circuit according to claim 1, wherein the bandgap reference voltage circuit comprises a first MOS transistor (P1) and a second MOS transistor (P2), a fourth MOS transistor (N4) and a fifth MOS transistor (N5), a first transistor (Q1) and a second transistor (Q2), a first resistor (R1);

The source electrodes of the first MOS transistor (P1) and the second MOS transistor (P2) are connected to a power supply end (VCC), the grid electrodes of the first MOS transistor (P1) and the second MOS transistor (P2) are connected, the drain electrode of the first MOS transistor (P1) is connected with the grid electrode, the drain electrode of the first MOS transistor (P1) is connected to the drain electrode of the fourth MOS transistor (N4), the drain electrode of the second MOS transistor (P2) is connected to the drain electrode of the fifth MOS transistor (N5), the grid electrodes of the fourth MOS transistor (N4) and the fifth MOS transistor (N5) are connected, and the drain electrode of the fifth MOS transistor (N5) is connected with the grid electrode; the source of the fourth MOS transistor (N4) is connected with the first resistor (R1) and then connected with the first pole of the first triode (Q1), the source of the fifth MOS transistor (N5) is connected with the first pole of the second triode (Q2), and the grids and the second poles of the first triode (Q1) and the second triode (Q2) are both connected with the grounding end.

3. The bandgap reference circuit according to claim 2, wherein the output circuit comprises a third MOS transistor (P3), a second resistor (R2), a third resistor (R3) and a first capacitor (C1);

the source electrode of the third MOS transistor (P3) is connected to a power supply end (VCC), the grid electrode of the third MOS transistor is connected to the grid electrodes of the first MOS transistor (P1) and the second MOS transistor (P2), the drain electrode of the third MOS transistor is connected to one end of a second resistor (R2), and the other end of the second resistor (R2) is connected to the source electrode of a fifth MOS transistor (N5); the third resistor (R3) is connected with the first capacitor (C1), the other end of the third resistor (R3) is connected with the drain electrode of the third MOS tube (P3), the other end of the first capacitor (C1) is connected with the ground terminal, and the connection point of the third resistor (R3) and the first capacitor (C1) is the output end of the output circuit.

4. The bandgap reference circuit according to claim 2, wherein the start-up circuit comprises a second capacitor (C2); the upper electrode plate of the second capacitor (C2) is connected to a power supply end (VCC), and the lower electrode plate is connected to the gates of the fourth MOS transistor (N4) and the fifth MOS transistor (N5).

5. The bandgap reference circuit according to claim 2, wherein the start-up circuit comprises a second capacitor (C2); the upper electrode plate of the second capacitor (C2) is connected to the gates of the first MOS transistor (P1) and the second MOS transistor (P2), and the lower electrode plate is connected to the ground terminal.

6. The bandgap reference circuit according to claim 2, wherein the first MOS transistor (P1) and the second MOS transistor (P2) are PMOS transistors.

7. The bandgap reference circuit according to claim 2, wherein the fourth MOS transistor (N4) and the fifth MOS transistor (N5) are NMOS transistors.

Technical Field

The invention belongs to the technical field of power electronics, and particularly relates to a band-gap reference circuit.

Background

in most system applications, a precise reference voltage is necessary. Generally, under conventional processes, a standard Bandgap reference Circuit (Bandgap Circuit) is employed. Normally, there are two stable states after the bandgap reference circuit is powered on: in order to enable the band-gap reference circuit to enter the working state stably after being electrified, a starting circuit must be additionally arranged during design, and the band-gap reference circuit is ensured to enter the working state certainly after being electrified.

Under a conventional CMOS process, there are generally two circuit designs of a conventional low power consumption bandgap reference circuit including a start-up circuit.

As shown in fig. 1, the first circuit is a power-consumption-free circuit of the starting circuit, and the left dotted-line box is a starting circuit which is composed of three devices including a large resistor, a capacitor and a PMOS transistor.

as shown in fig. 2, the second is a start-up circuit requiring extra power consumption, and the left dotted box is a start-up circuit composed of four devices including a large resistor, two NMOS transistors and a PNP transistor.

From the point of view of circuit architecture, the bandgap reference circuit itself is a positive feedback loop. The effect of the starting circuit in fig. 1 is to add a disturbance, the starting circuit in fig. 2 is forced to a weak bias state to work, and then after the positive feedback of the circuit works to a normal working state, the loop gain is reduced to be below 0dB, and the band gap reference circuit works stably.

These two kinds of start-up circuits each have advantages and disadvantages: the starting circuit of fig. 1 has the advantage of no power consumption, but has the disadvantage that the starting circuit has no effect if the power-on time exceeds the time constant R1 × C1; the starting circuit of fig. 2 has the obvious disadvantage of requiring power consumption, the advantage of ensuring that the starting circuit is certainly effective.

With the more advanced integrated circuit technology, the working voltage is lower, the green environmental protection is promoted, the power consumption is required to be lower, the starting circuit is required to be more reliable, and no power consumption current exists.

disclosure of Invention

the purpose of the invention is as follows: in view of the above problems, the present invention provides a bandgap reference circuit, which provides a start circuit that does not require power consumption and ensures start-up.

The technical scheme is as follows: in order to realize the purpose of the invention, the technical scheme adopted by the invention is as follows: a band-gap reference circuit comprises a starting circuit, a band-gap reference voltage circuit and an output circuit; the starting circuit is connected with the band-gap reference voltage circuit and used for providing voltage required by starting for the band-gap reference voltage circuit, and the band-gap reference voltage circuit is used for generating band-gap reference voltage and outputting the band-gap reference voltage through the output circuit; the starting circuit is composed of a capacitor, one end of the capacitor is connected to a power supply end, and the other end of the capacitor is connected to the band-gap reference voltage circuit.

Further, the band gap reference voltage circuit comprises a first MOS tube, a second MOS tube, a fourth MOS tube, a fifth MOS tube, a first triode, a second triode and a first resistor; the source electrodes of the first MOS tube and the second MOS tube are connected to a power supply end, the grid electrodes of the first MOS tube and the second MOS tube are connected, the drain electrode of the first MOS tube is connected with the grid electrode, the drain electrode of the first MOS tube is connected with the drain electrode of the fourth MOS tube, the drain electrode of the second MOS tube is connected with the drain electrode of the fifth MOS tube, the fourth MOS tube is connected with the grid electrode of the fifth MOS tube, and the drain electrode of the fifth MOS tube is connected with the grid electrode; the source electrode of the fourth MOS tube is connected with the first resistor and then connected to the first pole of the first triode, the source electrode of the fifth MOS tube is connected to the first pole of the second triode, and the grid electrodes and the second pole electrodes of the first triode and the second triode are both connected to the grounding terminal.

Furthermore, the output circuit comprises a third MOS transistor, a second resistor, a third resistor and a first capacitor; the source electrode of the third MOS tube is connected to a power supply end, the grid electrode of the third MOS tube is connected to the grid electrodes of the first MOS tube and the second MOS tube, the drain electrode of the third MOS tube is connected to one end of the second resistor, and the other end of the second resistor is connected to the source electrode of the fifth MOS tube; the third resistor is connected with the first capacitor, the other end of the third resistor is connected with the drain electrode of the third MOS tube, the other end of the first capacitor is connected with the grounding end, and the connection point of the third resistor and the first capacitor is the output end of the output circuit.

Further, the start-up circuit includes a second capacitor; the upper electrode plate of the second capacitor is connected to a power supply end, and the lower electrode plate of the second capacitor is connected to the grids of the fourth MOS tube and the fifth MOS tube.

Further, the start-up circuit includes a second capacitor; the upper electrode plate of the second capacitor is connected to the grids of the first MOS tube and the second MOS tube, and the lower electrode plate is connected to the grounding end.

Furthermore, the first MOS tube and the second MOS tube are PMOS tubes.

Furthermore, the fourth MOS tube and the fifth MOS tube are NMOS tubes.

Has the advantages that: the starting circuit of the band-gap reference circuit is composed of a capacitor, has a simple structure, can be reliably started without power consumption, and ensures stable output of the band-gap reference circuit.

Drawings

FIG. 1 is a schematic diagram of a prior art power-free start-up circuit;

FIG. 2 is a schematic diagram of a prior art start-up circuit requiring additional power consumption;

FIG. 3 is a schematic diagram of a bandgap reference circuit of the present invention;

FIG. 4 is a schematic diagram of a modified design of the bandgap reference circuit of the present invention;

FIG. 5 is a simulation diagram of the start-up transient timing when the power-up time is 1 us;

FIG. 6 is a simulation diagram of the start-up transient timing at a power-up time of 10 us;

FIG. 7 is a simulation diagram of the start-up transient timing at a power-up time of 100 us.

Detailed Description

The technical solution of the present invention is further described below with reference to the accompanying drawings and examples.

As shown in fig. 3, the bandgap reference circuit of the present invention includes a start circuit, a bandgap reference voltage circuit and an output circuit; the starting circuit is connected with the band-gap reference voltage circuit and used for providing voltage required by starting for the band-gap reference voltage circuit, and the band-gap reference voltage circuit is used for generating band-gap reference voltage and outputting the band-gap reference voltage through the output circuit; the starting circuit is composed of a capacitor, one end of the capacitor is connected with a power supply end, and the other end of the capacitor is connected with the band-gap reference voltage circuit.

the band-gap reference voltage circuit comprises a first MOS transistor P1, a second MOS transistor P2, a fourth MOS transistor N4, a fifth MOS transistor N5, a first triode Q1, a second triode Q2 and a first resistor R1; the start-up circuit comprises a second capacitor C2; the output circuit comprises a third MOS transistor P3, a second resistor R2, a third resistor R3 and a first capacitor C1. The first MOS transistor P1 and the second MOS transistor P2 are PMOS transistors, and the fourth MOS transistor N4 and the fifth MOS transistor N5 are NMOS transistors.

The source electrodes of the first MOS transistor P1 and the second MOS transistor P2 are connected to a power supply end VCC, the grid electrodes of the first MOS transistor P1 and the second MOS transistor P2 are connected, the drain electrode of the first MOS transistor P1 is connected with the grid electrode, the drain electrode of the first MOS transistor P1 is connected with the drain electrode of the fourth MOS transistor N4, the drain electrode of the second MOS transistor P2 is connected with the drain electrode of the fifth MOS transistor N5, the grid electrodes of the fourth MOS transistor N4 and the fifth MOS transistor N5 are connected (point A), and the drain electrode of the fifth MOS transistor N5 is connected with the grid electrode; the source of the fourth MOS transistor N4 is connected to the first resistor R1 and then to the first pole of the first transistor Q1, the source of the fifth MOS transistor N5 is connected to the first pole of the second transistor Q2, and the gates and the second poles of the first transistor Q1 and the second transistor Q2 are both connected to the ground GND.

The upper plate of the second capacitor C2 is connected to the power supply terminal VCC, and the lower plate is connected to the gates of the fourth MOS transistor N4 and the fifth MOS transistor N5.

the source of the third MOS transistor P3 is connected to a power supply terminal VCC, the gate is connected to the gates of the first MOS transistor P1 and the second MOS transistor P2, the drain is connected to one end of the second resistor R2, and the other end of the second resistor R2 is connected to the source of the fifth MOS transistor N5; the third resistor R3 is connected to the first capacitor C1, the other end of the third resistor R3 is connected to the drain of the third MOS transistor P3, the other end of the first capacitor C1 is connected to the ground GND, and the connection point of the third resistor R3 and the first capacitor C1 is the output terminal VREF of the output circuit.

The invention skillfully utilizes the electric quantity/voltage holding characteristic of the capacitor, and in the power-on process, because the first capacitor C1 exists, the zero voltage difference is basically kept between the point A and the power supply end, and the voltage of the point A is the power supply voltage or is slightly lower than the power supply voltage in the power-on process, so that a strong bias is applied to the grids of the fourth MOS tube N4 and the fifth MOS tube N5, and then the band-gap reference circuit starts to work. Along with the circuit operation, the electric capacity normal charge-discharge, first electric capacity C1 both ends voltage resumes normally, and the stable output of band gap reference circuit.

The start-up circuit of the present invention is modified as shown in fig. 4, wherein the upper plate of the second capacitor C2 is connected to the gates of the first MOS transistor P1 and the second MOS transistor P2, and the lower plate is connected to the ground GND.

The comparison of the power-on starting sequence of the bandgap reference circuit of the present invention with the prior art is shown in fig. 5, and when the power-on time is 1us, each curve in the starting transient sequence simulation diagram is respectively: VCC is power supply voltage, and the time from 0V to 3V is 1 us; VREF1 is the Bandgap reference voltage output for the start-up circuit of fig. 1; VREF2 is the Bandgap reference voltage output under the start-up circuit of fig. 2; VREF _ PT is the Bandgap reference voltage output under the start-up circuit of the present invention. It can be seen from fig. 4 that the Bandgap circuit is successfully enabled by all three kinds of enabling circuits.

As shown in fig. 6, in the simulation diagram of the start-up transient timing of the power-on time 10us, the power supply voltage VCC is 3V, and the time from 0V to 3V is 10 us. As shown in fig. 7, in the simulation diagram of the start-up transient timing of the power-on time 100us, the power supply voltage VCC is 3V, and the time from 0V to 3V is 100 us. As can be seen from fig. 6 and 7, the latter two start-up circuits successfully start up the Bandgap circuit and output the rated reference voltage of 1.197V, while the first start-up circuit fails, and the Bandgap circuit outputs only less than 300mV, which is far from the rated output voltage.

the comparison of fig. 5, 6 and 7 clearly shows that the first starting circuit cannot be started when the power-on time is slow, but the starting circuit of the present invention not only ensures the starting effect, but also has no power consumption requirement.