CN111458554B

CN111458554B - High-precision current monitoring circuit

Info

Publication number: CN111458554B
Application number: CN202010424547.XA
Authority: CN
Inventors: 李晴平; 曹天霖
Original assignee: Hangzhou Hongxin Microelectronics Technology Co ltd
Current assignee: Hangzhou Hongxin Microelectronics Technology Co ltd
Priority date: 2020-05-19
Filing date: 2020-05-19
Publication date: 2022-07-19
Anticipated expiration: 2040-05-19
Also published as: CN111458554A

Abstract

The invention realizes a wide-range and high-precision current monitoring circuit, which adjusts the voltages of a point D and a point E to be equal by introducing an AMP feedback circuit with an error amplifier, enables the voltages of a point B and a point C to be equal by the current mirror relationship of N1 and N2, and realizes the final high-precision current monitoring by two-way feedback.

Description

High-precision current monitoring circuit

Technical Field

The invention relates to the technical field of integrated circuits, in particular to a wide-range high-precision current monitoring circuit.

Background

For a high voltage current mode load, the circuit design for monitoring the current on the load is exemplified by APD (photo diode): an APD (photodiode) is an active current load, the actual current flowing through it is IAPD, and the current flowing through it is monitored, which is IMOUT. The traditional Current detection circuit containing a Current-mirror (mirror Current source) has no feedback link, and cannot realize high-precision detection in a wide range, so that IMOUT is equal to IAPD.

Disclosure of Invention

In order to monitor the current more accurately, the invention provides a high-precision current monitoring circuit capable of realizing a wide range.

In order to achieve the purpose, the invention is realized by the following technical scheme:

a high-precision current monitoring circuit includes a conventional current monitoring circuit and an error Amplifier (AMP) feedback circuit.

The traditional current monitoring circuit comprises PMOS tubes P1-P10, NMOS tubes N1 and N2, a Zener diode ZENER and a resistor R2. P5 source, P6 source, P9 source, ZENER cathode, R2 upper end, 5 devices are connected and connected to power supply BIAS. The lower ends of a P grid electrode, a P source electrode and a R electrode are connected to form a node A, a P drain electrode, a P source electrode and a P grid electrode are connected to form a node B, a P drain electrode, a P grid electrode and a P source electrode are connected to form a node C, a P grid electrode, a P drain electrode, a P grid electrode and an N drain electrode are connected to form a node E, an N grid electrode and an N grid electrode are connected to form a node F, a P drain electrode and a P source electrode are connected to form a node G, a P drain electrode, an N drain electrode and an N grid electrode are connected, an N source electrode and a P source electrode are connected, a P drain electrode, a P grid electrode and a P source electrode are connected with a GND, a P grid electrode, an upper end of R and a ZENER anode are connected, the P grid electrode is externally connected with an error amplifier AMP, the P drain electrode is IAPD, and the P drain electrode is IMOUT.

The error amplifier AMP feedback circuit includes an error amplifier AMP, a resistor R3, and a resistor R4. The upper end of the resistor R3 is connected with the drain electrode of the traditional current monitoring circuit P10 to form a node H, the lower end of the resistor R3, the upper end of the resistor R4 and the positive input end of the error amplifier AMP are connected to form a voltage feedback point VSAMPLE, the reverse input end of the error amplifier AMP is connected with a reference voltage V1P23, and the output of the error amplifier AMP is connected with the grid electrode of the P3 to form a node D.

The working principle of the invention is as follows: a high-precision current monitoring circuit has two more feedbacks compared with the traditional mirror structure. And the voltages of the point D and the point E are adjusted to be equal through an error Amplifier (AMP) feedback circuit, the voltages of the point B and the point C are equal through the mirror current mirror relation of N1 and N2, and the final high-precision current monitoring is realized through two-path feedback. The circuit feeds back the IAPD current to the point A, then feeds back the point A to the point D, simultaneously feeds back the mirrors of N1 and N2 to the points E and F, feeds back the points E and F to the points B and C, and feeds back the point D to the point B, so that the voltages of the points B and C are consistent finally.

Compared with the prior art, the invention has the following advantages:

1. compared with the traditional current monitoring circuit, the current monitoring circuit has two more feedbacks, and the monitoring precision is greatly improved.

2. The error amplifier AMP adopted by the invention can reduce the gain to a certain extent by adding P11-P14 on the basis of the traditional error amplifier AMP, does not need compensation, and simultaneously avoids using high-voltage pipes for P8 and P9 by using a diode connection method of P11-P14, thereby saving the area.

3. The high-precision current monitoring circuit can realize high-voltage isolation: the MOS transistors (not including the MOS transistor inside the error amplifier AMP) except P1, P3 and P7 are forced to work in a low voltage range of the regulated voltage drop of the potential difference Zener through the stabilized voltage drop of the Zener transistors, usually around 7V.

Drawings

FIG. 1 is a schematic circuit diagram of a high-precision current monitoring circuit according to the present invention

FIG. 2 is a schematic diagram of an error amplifier AMP of a high-precision current monitoring circuit according to the present invention

Detailed Description

Embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

Example 1

As shown in fig. 1, a high-precision current monitoring circuit of the present invention includes: PMOS tubes P1-P10, NMOS tubes N1 and N2, a Zener diode ZENER, an error amplifier AMP, and resistors R1-R4. The specific connection mode is as follows: p5 source, P6 source, P9 source, ZENER cathode, R2 upper end, 5 devices are connected and connected to power supply BIAS. The P5 grid electrode, the P6 grid electrode, the P9 grid electrode, the P8 source electrode, the P4 source electrode and the R2 are connected to form a node A, the P5 drain electrode, the P3 source electrode and the P4 grid electrode are connected to form a node B, the P6 drain electrode, the P8 grid electrode and the P7 source electrode are connected to form a node C, the error amplifier AMP output is connected with the P3 grid electrode to form a node D, the P7 grid electrode, the P8 drain electrode, the P10 grid electrode and the N2 drain electrode are connected to form a node E, the N1 grid electrode and the N2 grid electrode are connected to form a node F, the P9 drain electrode and the P10 source electrode are connected to form a node G, the R3 grid electrode is connected with the P3 drain electrode to form a node H, the P3 drain electrode, the N3 drain electrode and the N3 grid electrode are connected, the N3 source electrode, the P3 source electrode is connected, the P3 grid electrode 3, the P3 drain electrode is connected with the P3 drain electrode, the P3 drain electrode is connected with the P3 drain electrode 3, the P3 drain electrode is connected with the P3 drain electrode, the P3 is connected with the P3 drain electrode, the P3 drain electrode is connected with the P3, the P3 drain electrode is connected with the P3 drain electrode, the P3 drain electrode is connected with the P3 drain electrode, the P3 drain electrode is connected with the P3 drain electrode, the P3 drain electrode is connected with the error amplifier is connected with the P3 drain electrode, and the P3 drain electrode is connected with the P3 drain electrode, the P3 drain electrode is connected with the P3 drain electrode, and the P3 drain electrode is connected with the P3 drain electrode, and the P3 drain electrode is connected with the P3 drain electrode, the P3 drain electrode is connected with the error amplifier is connected with the P3 drain electrode is connected with the P3 drain electrode, the P3 drain electrode. The lower end of the resistor R3, the upper end of the resistor R4 and the positive input end of the error amplifier AMP are connected to form a voltage feedback point VSAMPLE, and the reverse input end of the error amplifier AMP is connected with a reference voltage V1P 23.

The specific working principle is as follows: high accuracy current monitoring is achieved by ensuring B, D to respectively correspond to C, E point voltages. If IAPD is not equal to the current flowing through P9, the voltage of point D and point E is correspondingly adjusted through negative feedback of AMP, and finally the current flowing through point P5 is equal to the current flowing through point P9, namely the same potential is applied to point D and point E. In conjunction with the feedback of AMP, the mirror structure feedback of N1 and N2 makes the currents flowing through P4 and P8 equal, and the source terminals of P4 and P8 are connected together, so that the voltages at the point B and the point C are forced to be equal to ensure that the currents at N1 and N2 are equal.

IAPD increases so that the voltage at point a decreases, while since R2 is a fixed resistance, the current flowing through R2 increases, the voltage at point F increases, the voltage at point B decreases, and the sum of the currents flowing through N1 and N2 increases. In order to ensure IMOUT — IAPD, it is important to ensure that the voltages at the three terminals P5 and P6 are completely consistent, i.e. the voltages at the points B and C are maximally equalized. Since the sum of the currents flowing through N1 and N2 increases, if the voltages at point B and point C are equal, the currents of N1 and N2 increase equally. Assuming that the N1 and N2 currents do not increase to the same extent, the N1 current must be greater than the N2 current. When the current of N1 is larger than the current of N2, the voltage at point B is smaller than the voltage at point C, and the voltage at point E is reduced along with the increase of IAPD current, so that VSAMPLE is increased, the voltage at point D is increased through the feedback action of error amplifier AMP, the voltage at point B is increased, and finally the voltage at point B and the voltage at point C are equal. Similarly, when the IAPD is reduced, the voltage at the point B is equal to the voltage at the point C. When the voltages of the three ends P5 and P6 are completely consistent, IMOUT and IAPD can guarantee high-precision equality.

Further, P3 and P7 are understood as cascade tubes, further improving accuracy. Since the IAPD and IMOUT terminals are external ports, typically low voltage ports, the P3 and P7 also serve to isolate the high and low voltages.

Example 2

As shown in FIG. 2, the invented error amplifier AMP of a high-precision current monitor circuit of the present invention has four more PMOS transistors P11-P14 compared to a conventional operational amplifier. The source of the P11 is connected to a power BIAS, the grid of the P11, the drain of the P11 and the source of the P12 are connected, the grid of the P12, the drain of the P12 and the source of the P13 are connected, and the grid of the P13, the drain of the P13 and the source of the P14 are connected with other devices in the error amplifier in parallel and connected with an output OUT. VDD and BIAS are low and high voltage power supply, respectively, Isink _ BIAS is the current BIAS, PM7 and PM10 are high voltage PMOS.

Further, the four PMOS of P11 to P14 of the error amplifier AMP of the present invention reduce the switching gain of the error amplifier AMP by reducing the output resistance;

further, the four PMOS of the error amplifier AMP of the present invention P11 to P14 play a role of clamp protection of P8 and P9. The gain of the error amplifier AMP cannot be too large, and if the gain is too large, the output will be saturated, so that the voltage at the point D is too high, which affects the current output capability of the circuit.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and improvements can be made without departing from the spirit of the present invention, and these modifications and improvements should also be considered as within the scope of the present invention.

Claims

1. The utility model provides a high accuracy current monitoring circuit, includes traditional current monitoring circuit, its characterized in that: further comprising an error amplifier AMP feedback circuit;

the conventional current monitoring circuit includes: PMOS tubes P1-P10, NMOS tubes N1 and N2, Zener diodes ZENER, resistors R2, P5 source electrodes, P6 source electrodes, P9 source electrodes, ZENER cathodes and the upper ends of R2, wherein 5 devices are connected in parallel with a power supply BIAS; a P5 grid electrode, a P6 grid electrode, a P9 grid electrode, a P8 source electrode, a P4 source electrode, a R2 lower end are connected to form a node A, a P5 drain electrode, a P3 source electrode and a P4 grid electrode are connected to form a node B, a P6 drain electrode, a P8 grid electrode and a P7 source electrode are connected to form a node C, a P7 grid electrode, a P8 drain electrode, a P10 grid electrode and an N2 drain electrode are connected to form a node E, an N1 grid electrode and an N2 grid electrode are connected to form a node F, a P9 drain electrode and a P10 source electrode are connected to form a node G, a P4 drain electrode, an N1 drain electrode and an N1 grid electrode are connected, an N1 source electrode, an N2 source electrode and a P2 source electrode are connected, a P2 drain electrode, a P2 grid electrode and a P2 source electrode are connected, a P2 drain electrode is connected with a R2 lower end of the GND, a P2 grid electrode is externally connected with the drain electrode of the drain electrode AMP, and the drain electrode of the ZENER 2 of the P2 is connected with the IAPD of the drain electrode of the P2 of the drain electrode of the external connection of the drain electrode of the external circuit;

the IAPD is an actual current flowing through the active current load;

the IMOUT is monitoring current flowing through an active current load;

the error amplifier AMP feedback circuit includes: an error amplifier AMP and a resistor R3, a resistor R4; the upper end of the resistor R3 is connected with the drain electrode of the traditional current monitoring circuit P10 to form a node H, the lower end of the resistor R3, the upper end of the resistor R4 and the positive input end of the error amplifier AMP are connected to form a voltage feedback point VSAMPLE, the reverse input end of the error amplifier AMP is connected with a reference voltage V1P23, and the output of the error amplifier AMP is connected with the grid electrode of P3 to form a node D;

compared with the conventional operational amplifier, the error amplifier AMP has four more PMOS tubes P11-P14, a P11 source electrode is connected with a power supply BIAS, a P11 grid electrode, a P11 drain electrode and a P12 source electrode are connected, a P12 grid electrode, a P12 drain electrode and a P13 source electrode are connected, and a P13 grid electrode, a P13 drain electrode and a P14 source electrode and other devices in the error amplifier are connected with an output OUT in parallel.

2. A high accuracy current monitor circuit according to claim 1, wherein: the PMOS transistors P3 and P7 in the conventional current monitoring circuit are respectively connected to the IPAD terminal and the IMOUT terminal, and may be MOS transistors of a drain-source stacked structure cascade.

3. A high accuracy current monitoring circuit according to claim 1, wherein: the monitoring object can be a photodiode current load, and can also be other types of current loads.