# US 12,601,767 B2 · Current sense amplifier

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- Number: US 12,601,767 B2
- Document ID: US12601767B2
- Status: Granted
- Kind: B2
- Application number: 18/642,202
- Filed: 2024-04-22
- Published: 2025-07-24
- Granted: 2026-04-14
- Earliest claimed: 2024-01-22
- Assignees: Will Semiconductor (Shanghai) Co. Ltd.
- Applicants: Will Semiconductor (Shanghai) Co. Ltd.
- Inventors: Hiroyuki Kimura
- Web page: https://patentgrep.com/patent/US12601767B2

## CPC

- G01R 19/0023: {Measuring currents or voltages from sources with high internal resistance by means of measuring circuits with high input impedance, e.g. OP-amplifiers (electrostatic instruments G01R5/28; measuring electrostatic potential G01R15/165; measuring electrostatic fields G01R29/12; amplifiers per se H03F)}
- G01R 19/10: Measuring sum, difference or ratio
- H03F 3/45475: {using IC blocks as the active amplifying circuit}
- H03F 2200/129: there being a feedback over the complete amplifier
- H03F 2200/261: Amplifier which being suitable for instrumentation applications
- H03F 2200/462: the current being sensed
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)
- H03F: AMPLIFIERS

## Abstract

[Problem to be solved] The disclosure is to deal with a wide range of DC voltages in the input. [Solution] In a current sense amplifier 100, an upper side voltage and a lower side voltage of a current detection resistor 2 are input thereto, and an output corresponding to a difference between the upper side voltage and the lower side voltage is obtained. A common mode voltage suppressor 12 includes: voltage division resistors R6a and R6b, the upper side voltage and the lower side voltage being supplied to the two ends thereof, and a division voltage being obtained; a first transistor M1, the upper side voltage being input to one end thereof, and the other end thereof being connected to a predetermined power supply; and a second transistor M2, the lower side voltage being input to one end thereof, and the other end thereof being connected to a predetermined power supply. A control end of the first transistor M1 and a control end of the second transistor M2 are commonly connected and the division voltage is input thereto.

## Claims

### Claim 1

A current sense amplifier having inputs being connected to an upper side voltage and a lower side voltage of a current detection resistor, and configured to provide an output corresponding to a difference between the upper side voltage and the lower side voltage, the current sense amplifier comprises;
a common mode voltage suppressor that suppresses a common mode voltage in the upper side voltage and the lower side voltage,
the common mode voltage suppressor including:
a voltage division resistor having one end being connected to the upper side voltage and the other end being connected to the lower side voltage, and configured to provide a division voltage;
a first transistor having one end being connected to the upper side voltage and the other end being connected to a predetermined power supply; and
a second transistor having one end being connected to the lower side voltage and the other end thereof being connected to the predetermined power supply; and
a control end is commonly connected to a gate of the first transistor and a gate of the second transistor, and the division voltage is inputted to the control end.

### Claim 2 (depends on 1)

The current sense amplifier according to claim 1, wherein
the first and second transistors are n-channel MOSFETs.

### Claim 3 (depends on 1)

The current sense amplifier according to claim 1, further comprising:
a preamplifier having inputs being connected to the upper side voltage and the lower side voltage, and outputting a positive output and a negative output corresponding to a voltage difference between the upper side voltage and the lower side voltage;
and a post-amplifier having inputs being connected to the positive output and the negative output of the preamplifier.

### Claim 4 (depends on 3)

The current sense amplifier according to claim 3, wherein
the post-amplifier is supplied with a reference voltage, and sets an offset voltage of the output of the post-amplifier by a combination of resistors entering between an input end of the reference voltage and two outputs of the preamplifier.

### Claim 5 (depends on 4)

The current sense amplifier according to claim 4, wherein
the reference voltage has two types and is switchable.

### Claim 6 (depends on 1)

The current sense amplifier according to claim 1, further comprising:
a first constant current source, which supplies a constant current to one end of the first transistor; and
a second constant current source, which supplies a constant current to one end of the second transistor.