# US 7,466,194 B2 · DC offset mitigation in a single-supply amplifier

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- Number: US 7,466,194 B2
- Document ID: US7466194B2
- Status: Granted
- Kind: B2
- Application number: 11/737,616
- Filed: 2007-04-19
- Published: 2008-04-24
- Granted: 2008-12-16
- Earliest claimed: 2006-05-18
- Assignees: Cirrus Logic, Inc.
- Inventors: Babak Mazda; Rahul Shinkre; Farzad Sahandiesfanjani; Maziar Sayyedi; Krishna Prasad Sarangapani
- Web page: https://patentgrep.com/patent/US7466194B2

## CPC

- H03F 3/45623: {using switching means}
- H03F 3/2173: {of the bridge type}
- H03F: AMPLIFIERS

## Abstract

An amplifier is described which includes a first loop including a first amplifier stage having an offset voltage associated therewith. An output stage includes two switching devices in a bridge configuration configured to be coupled between a supply voltage and ground. An output of the bridge configuration is configured to be coupled to a load. The first loop is characterized by a first gain. A decoupling capacitor is configured to be coupled to the load. A second loop which includes the first amplifier stage is configured to charge the decoupling capacitor to a first voltage generated with reference to the offset voltage before operation of the switching devices is enabled. The second loop is characterized by a second gain. The first and second gains are substantially the same such that when operation of the switching devices is enabled a second voltage at the output of the half-bridge configuration is substantially the same as the first voltage.

## Claims

### Claim 1

An amplifier, comprising:
a first loop including a first amplifier stage having an offset voltage associated therewith, and an output stage comprising two switching devices in a bridge configuration configured to be coupled between a supply voltage and ground, an output of the bridge configuration being configured to be coupled to a load, the first loop being characterized by a first gain;
a decoupling capacitor configured to be coupled to the load; and
a second loop including the first amplifier stage, the second loop being configured to charge the decoupling capacitor to a first voltage generated with reference to the offset voltage before operation of the switching devices is enabled, the second loop being characterized by a second gain, wherein the first and second gains are substantially the same such that when operation of the switching devices is enabled a second voltage at the output of the half-bridge configuration is substantially the same as the first voltage.

### Claim 2 (depends on 1)

The amplifier of claim 1 wherein the first loop comprises a linear amplifier.

### Claim 3 (depends on 2)

The amplifier of claim 2 wherein the linear amplifier comprises one of a class AB amplifier, a class B amplifier, class G amplifier, and a class H amplifier.

### Claim 4 (depends on 1)

The amplifier of claim 1 wherein the first loop comprises a switching amplifier.

### Claim 5 (depends on 4)

The amplifier of claim 4 wherein the switching amplifier comprises a class D amplifier.

### Claim 6 (depends on 1)

The amplifier of claim 1 wherein the first loop comprises an audio amplifier and the load comprises a speaker.

### Claim 7 (depends on 1)

The amplifier of claim 1 wherein the first loop comprises a single stage comprising the first amplifier stage.

### Claim 8 (depends on 1)

The amplifier of claim 1 wherein the first loop comprises a plurality of stages including the first amplifier stage.

### Claim 9 (depends on 1)

An electronic system comprising the amplifier of claim 1.