CN111721986A - A Wide Input Common Mode Voltage Range Current Sense Amplifier Circuit - Google Patents

Abstract

The invention discloses a wide-input common-mode voltage range current detection amplifier circuit, which belongs to the technical field of current detection amplifier circuits. During current detection, an operational amplifier with a limited input common-mode range in a low-voltage domain realizes an ultra-wide-range common-mode voltage input during current detection. , the voltage drop of high voltage is on the resistance, all operation circuits are realized by low-voltage devices, no additional high-voltage voltage source and high-voltage devices are needed, and the required functions can be realized in an ultra-small area.

Description

A Wide Input Common Mode Voltage Range Current Sense Amplifier Circuit

technical field

The invention relates to a current detection amplifier circuit, in particular to a current detection amplifier circuit with a wide input common mode voltage range, belonging to the technical field of current detection amplifier circuits.

Background technique

In the power supply system, the load current needs to be detected in real time. In the prior art, when the detection point is on the power supply line or the ground line, the input common mode voltage is the power supply voltage or the ground line voltage, and the comparator is easy to implement. If you need to directly detect the voltage on the load When the current is running, the common mode voltage varies widely when the load is turned on and off. Due to the inductive load and the wiring inductance, it may even be higher than the power supply voltage or lower than the ground level. The input common mode range of the corresponding operational amplifier is required. From negative voltage to higher than the power supply voltage, additional high-voltage voltage devices are required to occupy the chip area and increase the cost. Therefore, a wide-input common-mode voltage range current detection amplifier circuit is designed to optimize the above problems.

SUMMARY OF THE INVENTION

The main purpose of the present invention is to provide a wide input common mode voltage range current detection amplifier circuit.

Object of the present invention can be achieved by adopting the following technical solutions:

A wide-input common-mode voltage range current detection amplifier circuit includes an operational amplifier OPA1, the positive pole of the operational amplifier OPA1 is connected to a reference level, and the negative pole of the operational amplifier OPA1 is electrically connected to the source of the field effect transistor MN1 and the field effect The source of the tube MP1, the negative terminal of the operational amplifier OPA1 is also connected to one end of the resistor R2, the other end of the resistor R2 is connected to the external terminal SN as the input detection terminal, and the output terminal of the operational amplifier OPA1 is electrically connected to the field effect transistor MN1 The gate of the field effect transistor MP1, the gate of the field effect transistor MP2 and the gate of the field effect transistor MN2, the drain of the field effect transistor MP1 is connected to the drain of the field effect transistor MN3, and the source of the field effect transistor MN3 pole ground.

Preferably, the source of the field effect transistor MN3 is also connected to the source of the field effect transistor MN4, the gate of the field effect transistor MN3 is connected to the gate of the field effect transistor MN4, and the drain of the field effect transistor MN3 is connected. The pole is connected to the gate of the field effect transistor MN3.

Preferably, the source of the field effect transistor MN2 is connected to the drain of the field effect transistor MP2, the drain of the field effect transistor MP2 is connected to the drain of the field effect transistor MN4, and the drain of the field effect transistor MP4 is connected to the The drain of the FET MN2.

Preferably, the gate of the field effect transistor MP4 is connected to the gate of the field effect transistor MP3, the sources of the field effect transistors MP3 and MP4 are connected to each other and connected to the power supply VCC, and the drain of the field effect transistor MP3 is connected to the field effect transistor. The gate of the effect transistor MP3 and the source of the field effect transistor MN2 are connected to one end of the resistor R1.

Preferably, the other end of the resistor R1 is connected to the external terminal SP as an input detection end, one end of the resistor R1 is connected to one end of the resistor R2, one end of the resistor R1 is connected to one end of the resistor R3, and one end of the resistor R3 Also connect the negative terminal of the operational amplifier OPA2.

Preferably, the positive pole of the operational amplifier OPA2 is connected to the negative pole of the operational amplifier OPA1, the output terminal of the operational amplifier OPA2 outputs a voltage signal, and the other end of the resistor R3 is connected to the output terminal of the operational amplifier OPA2.

Preferably, VCC is an internal logic low voltage level, MPx is a PMOS transistor, MNx is an NMOS transistor, Rx is a resistor, and OPAx is an operational amplifier.

Preferably, OPA1, MN1, and MP1 on the left are operational amplifier circuits with classAB output stage, which function to make the level of point A equal to the level of Vref.

Preferably, the MP3 and MP4 current mirrors and the MN3 and MN4 current mirrors will mirror the current on R2 to make it flow through the resistor R1.

Preferably, MN2 and MP2 are cascaded MOSs of current mirrors, which are used to improve the channel length modulation effect of the current mirror MOSs

Beneficial technical effects of the present invention:

The present invention provides a wide-input common-mode voltage range current detection amplifier circuit. During current detection, an operational amplifier with a limited input common-mode range in a low-voltage domain is used to realize an ultra-wide-range common-mode voltage input, and the voltage drop of high voltage drops in the resistor. In the above, all operation circuits are realized by low-voltage devices, and there is no need to generate additional high-voltage voltage sources and use high-voltage devices, and can realize the required functions in an ultra-small area.

Description of drawings

Fig. 1 is a current detection circuit diagram in the prior art;

Fig. 2 is the selection circuit diagram of the current detection point in the prior art;

3 is a current detection circuit diagram of an ultra-wide range input common film voltage according to a preferred embodiment of a wide input common mode voltage range current detection amplifier circuit according to the present invention.

Detailed ways

In order to make the technical solution of the present invention clearer and clearer to those skilled in the art, the present invention will be described in further detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

As shown in FIG. 3, a wide-input common-mode voltage range current detection amplifier circuit includes an operational amplifier OPA1, the positive pole of the operational amplifier OPA1 is connected to the reference level, and the negative pole of the operational amplifier OPA1 is electrically connected to the field effect transistor MN1 The source of the field effect transistor MP1 and the source of the field effect transistor MP1, the negative pole of the operational amplifier OPA1 is also connected to one end of the resistor R2, the other end of the resistor R2 is connected to the external terminal SN as the input detection terminal, and the output terminal of the operational amplifier OPA1 is electrically The gate of field effect transistor MN1, the gate of field effect transistor MP1, the gate of field effect transistor MP2 and the gate of field effect transistor MN2 are sexually connected, and the drain of field effect transistor MP1 is connected to the drain of field effect transistor MN3, The source of the field effect transistor MN3 is grounded.

VCC is an internal logic low voltage level (such as 3.3V), MPx is a PMOS tube, MNx is an NMOS tube, Rx is a resistor, and OPAx is an operational amplifier.

OPA1, MN1 and MP1 on the left are operational amplifier circuits with classAB output stage, which function to make the level of point A equal to the level of Vref. MP3, MP4 current mirrors and MN3, MN4 current mirrors will mirror the current on R2 to flow through resistor R1. MN2 and MP2 are cascaded MOSs of current mirrors, which are used to improve the channel length modulation effect of the current mirror MOSs.

The loop of OPA2 forces the level of point B to be equal to the level of point A (ie, the Vref level).

IR1=(SP-VB)/R1=(SP-Vref)/R1;

IR2=(SN-VA)/R2=(SN-Vref)/R2;

Design R1=R2=R;

IR3=IR1-IR2=(SP-SN)/R;

Vout=VB-IR3*R3=Vref-(SP-SN)*R3/R.

When the SP/SN common mode voltage is greater than the voltage at point A, the current mirrors MN3 and MN4 work, the current flows from SP/SN through R2/R3, the current mirrors MN3 and MN4 reach the ground, and the input level of OPA2 is near the voltage at point A.

When the SP/SN common mode voltage is less than the voltage at point A, the current mirrors MP3 and MP4 work, the current flows from VCC to the current mirrors MP3 and MP4, and flows through R2/R3 to SP/SN, and the input level of OPA2 is near the voltage at point A.

In this way, the wide-range input common-mode level of SP/SN can be realized. By adjusting the current mirror current capability and the resistance values of R2 and R3, the input common-mode level can range from less than ground to greater than the power supply voltage. As long as the current capability of the current mirror is larger, the input common-mode voltage range is wider. Assuming that the maximum current capability of the current mirror is Imax, the input common-mode voltage range is

VCM=VA±Imax*R2.

In current detection, an operational amplifier with a limited input common-mode range in the low-voltage domain realizes an ultra-wide range of common-mode voltage input, and the high-voltage drop is on the resistor. All operational circuits are realized by low-voltage devices, and no additional high-voltage voltage is required The source and use of high-voltage devices can realize the required functions in an ultra-small area.

The above are only further embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Equivalent replacements or changes to the concept all belong to the protection scope of the present invention.

Claims (10)

1. A wide-input common-mode voltage range current detection amplifier circuit, characterized in that: comprising an operational amplifier OPA1, the positive pole of the operational amplifier OPA1 is connected to a reference level, and the negative pole of the operational amplifier OPA1 is electrically connected to the field effect transistor MN1 The source of the field effect transistor MP1 and the source of the field effect transistor MP1, the negative pole of the operational amplifier OPA1 is also connected to one end of the resistor R2, the other end of the resistor R2 is connected to the external terminal SN as the input detection terminal, and the output terminal of the operational amplifier OPA1 is electrically The gate of field effect transistor MN1, the gate of field effect transistor MP1, the gate of field effect transistor MP2 and the gate of field effect transistor MN2 are sexually connected, and the drain of field effect transistor MP1 is connected to the drain of field effect transistor MN3, The source of the field effect transistor MN3 is grounded. 2 . The wide-input common-mode voltage range current detection amplifier circuit according to claim 1 , wherein the source of the field effect transistor MN3 is also connected to the source of the field effect transistor MN4 , and the field effect The gate of the transistor MN3 is connected to the gate of the field effect transistor MN4, and the drain of the field effect transistor MN3 is connected to the gate of the field effect transistor MN3. 3. A wide-input common-mode voltage range current detection amplifier circuit according to claim 1, wherein the source of the field effect transistor MN2 is connected to the drain of the field effect transistor MP2, and the field effect transistor MP2 The drain of the field effect transistor MN4 is connected to the drain of the field effect transistor MP4, and the drain of the field effect transistor MP4 is connected to the drain of the field effect transistor MN2. 4. A wide-input common-mode voltage range current detection amplifier circuit according to claim 1, wherein the gate of the field effect transistor MP4 is connected to the gate of the field effect transistor MP3, and the field effect transistor MP3 The source of MP4 is connected to each other and the power supply VCC, the drain of the field effect transistor MP3 is connected to the gate of the field effect transistor MP3, and the source of the field effect transistor MN2 is connected to one end of the resistor R1. 5. A wide-input common-mode voltage range current detection amplifier circuit according to claim 1, wherein the other end of the resistor R1 is connected to the external terminal SP as an input detection end, and one end of the resistor R1 is connected to the resistor R1. One end of R2 is connected, one end of the resistor R1 is connected to one end of the resistor R3, and one end of the resistor R3 is also connected to the negative electrode of the operational amplifier OPA2. 6. A wide-input common-mode voltage range current detection amplifier circuit according to claim 1, wherein the positive pole of the operational amplifier OPA2 is connected to the negative pole of the operational amplifier OPA1, and the output terminal of the operational amplifier OPA2 outputs a voltage signal, And the other end of the resistor R3 is connected to the output end of the operational amplifier OPA2. 7. A wide-input common-mode voltage range current detection amplifier circuit according to claim 1, characterized in that: VCC is an internal logic low-voltage level, MPx is a PMOS tube, MNx is an NMOS tube, Rx is a resistance, and OPAx is a Operational Amplifier. 8. A wide-input common-mode voltage range current detection amplifier circuit according to claim 1, characterized in that: OPA1, MN1, and MP1 on the left are operational amplifier circuits with classAB output stage, and the functions are to make the level of point A, etc. at the Vref level. 9 . The wide-input common-mode voltage range current detection amplifier circuit according to claim 1 , wherein the MP3 and MP4 current mirrors and the MN3 and MN4 current mirrors mirror the current on R2 to make it flow through the resistor R1 . 10. A wide-input common-mode voltage range current detection amplifier circuit according to claim 1, characterized in that: MN2 and MP2 are cascade-connected MOSs of current mirrors, which are used to improve the channel length modulation effect of the current mirror MOSs .

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