# US 12,191,831 B2 · Amplifying device having high input impedance

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- Number: US 12,191,831 B2
- Document ID: US12191831B2
- Status: Granted
- Kind: B2
- Application number: 17/592,274
- Filed: 2022-02-03
- Published: 2022-08-11
- Granted: 2025-01-07
- Earliest claimed: 2021-02-08
- Assignees: Seoul National University R&Db Foundation
- Applicants: Seoul National University R&DB Foundation
- Inventors: Junyoung Park; Suhwan Kim
- Web page: https://patentgrep.com/patent/US12191831B2

## CPC

- H03F 3/45475: {using IC blocks as the active amplifying circuit}
- H03F 1/26: Modifications of amplifiers to reduce influence of noise generated by amplifying elements
- H03F 3/393: with field-effect devices
- H03F 2200/261: Amplifier which being suitable for instrumentation applications
- H03F 2203/45512: the FBC comprising one or more capacitors, not being switched capacitors, and being coupled between the LC and the IC
- H03F: AMPLIFIERS

## Abstract

An amplifying device includes a main amplifier; a first feedback circuit coupled between an input terminal of the main amplifier and an output terminal of the main amplifier; an input coupling circuit coupled between the input terminal of the main amplifier and a first node; and an amplifying feedback circuit coupled between the output terminal of the main amplifier and the first node, wherein the first feedback circuit and the amplifying feedback circuit are negative feedback circuits.

## Claims

### Claim 1

An amplifying device comprising:
a main amplifier;
a first feedback circuit coupled between an input terminal of the main amplifier and an output terminal of the main amplifier;
an input coupling circuit coupled between the input terminal of the main amplifier and a first node; and
an amplifying feedback circuit coupled between the output terminal of the main amplifier and the first node,
wherein the first feedback circuit and the amplifying feedback circuit are negative feedback circuits, and
wherein the amplifying feedback circuit includes:
a feedback amplifier;
a feedback output capacitor coupled between an output terminal of the feedback amplifier and the first node;
a feedback input capacitor coupled between an input terminal of the feedback amplifier and the output terminal of the main amplifier; and
an amplifying feedback capacitor coupled between the input terminal of the feedback amplifier and the output terminal of the feedback amplifier.

### Claim 2 (depends on 1)

The amplifying device of claim 1, wherein the input coupling circuit includes an input capacitor and the first feedback circuit includes a first feedback capacitor.

### Claim 3 (depends on 1)

The amplifying device of claim 1, further comprising a bias circuit providing a common voltage to the input terminal of the main amplifier.

### Claim 4 (depends on 1)

The amplifying device of claim 1, wherein the main amplifier is a differential amplifier, wherein each of the main amplifier and the first feedback circuit includes a chopping circuit therein, and wherein the amplifying device further includes a chopping circuit coupled to an input node thereof.

### Claim 5 (depends on 1)

The amplifying device of claim 1, wherein the main amplifier and the feedback amplifier are differential amplifiers.

### Claim 6 (depends on 5)

The amplifying device of claim 5, further comprising a chopping circuit coupled between the feedback input capacitor and the output terminal of the main amplifier.

### Claim 7 (depends on 6)

The amplifying device of claim 6, further comprising a chopping circuit coupled between the feedback output capacitor and the output terminal of the feedback amplifier and a chopping circuit coupled between the feedback input capacitor and the input terminal of the feedback amplifier.

### Claim 8 (depends on 1)

The amplifying device of claim 1, further comprising a second feedback circuit coupled between the output terminal of the main amplifier and the first node, wherein the second feedback circuit is a positive feedback circuit.

### Claim 9 (depends on 8)

The amplifying device of claim 8, wherein the second feedback circuit includes a second capacitor coupled between the output terminal of the main amplifier and the first node.

### Claim 10 (depends on 9)

The amplifying device of claim 9, wherein the main amplifier is a differential amplifier and the second feedback circuit further includes a chopping circuit coupled between the output terminal of the main amplifier and the second feedback capacitor.