# US 9,438,171 B2 · Multiplying current conveyor for amplifier

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- Number: US 9,438,171 B2
- Document ID: US9438171B2
- Status: Granted
- Kind: B2
- Application number: 14/603,686
- Filed: 2015-01-23
- Published: 2015-07-30
- Granted: 2016-09-06
- Earliest claimed: 2014-01-24
- Assignees: SnapTrack, Inc.
- Applicants: Snaptrack, Inc.
- Inventors: Russell Fagg
- Web page: https://patentgrep.com/patent/US9438171B2

## CPC

- H03F 1/0222: {by using a signal derived from the input signal}
- H03F 3/193: with field-effect devices (H03F3/195 takes precedence)
- H03F 3/24: of transmitter output stages
- H03F 3/345: with field-effect devices (H03F3/347 takes precedence)
- H03F 2200/456: A scaled replica of a transistor being present in an amplifier
- H03F 2200/91: the amplifier has a current mode topology
- H03F: AMPLIFIERS

## Abstract

A circuit having a first transistor being a common gate connected transistor and a second transistor, the second transistor being M times the size of the first transistor, the first and second transistors having commonly connected gates and commonly connected drains, wherein an apparatus is provided to regulate the source voltage of the second transistor to track the source voltage of the first transistor, wherein the current gain of the circuit is M+1.

## Claims

### Claim 1

A circuit having a first transistor being a common gate connected transistor and a second transistor, the second transistor being M times the size of the first transistor, the first and second transistors having commonly connected gates and commonly connected drains, wherein an apparatus is provided to regulate the source voltage of the second transistor to track the source voltage of the first transistor, wherein the current gain of the circuit is M+1, and wherein the drain of the first transistor provides the output of the circuit.

### Claim 2 (depends on 1)

The circuit of claim 1, wherein the apparatus comprises an amplifier having input terminals coupled to the sources of the first and second transistors and configured to regulate the source voltage of the second transistor.

### Claim 3

The circuit of claim wherein the output of the amplifier is coupled to the gate a third transistor, wherein the drain of the third transistor is coupled to the source of the second transistor, and wherein the output of the amplifier is configured to regulate the source voltage of the second transistor via the third transistor.

### Claim 4 (depends on 1)

The circuit of claim 1 wherein the drain of the first transistor is connected to one terminal of a current source.

### Claim 5 (depends on 4)

The circuit of claim 4, wherein the current source provides a biasing current for the circuit of ICC.

### Claim 6 (depends on 5)

The circuit of claim 5 wherein the current source provides a bias current of ICC*M/(1+M) to the second transistor.

### Claim 7 (depends on 5)

The circuit of claim 5 wherein the current source provides a bias current of ICC/(1+M) to the first transistor.

### Claim 8 (depends on 1)

A current conveyor comprising the circuit of claim 1.

### Claim 9 (depends on 1)

An envelope tracking power amplifier system comprising a power amplifier, wherein the power amplifier comprises the circuit of claim 1.

### Claim 10

A circuit having a first transistor being a common gate connected transistor and a second transistor, the second transistor being M times the size of the first transistor, the first and second transistors having commonly connected gates and commonly connected drains, wherein an apparatus is provided to regulate the source voltage of the second transistor to track the source voltage of the first transistor, wherein the current gain of the circuit is M+1, and wherein the source of the first transistor is connected to receive an input to the circuit.

### Claim 11 (depends on 10)

The circuit of claim 10 further comprising a third transistor having a gate connected to receive the input to the circuit, and for controlling the gate of the first transistor.

### Claim 12 (depends on 11)

The circuit of claim 11 wherein the drain of the third transistor is connected to the gate of the first transistor.

### Claim 13 (depends on 12)

The circuit of claim 12 wherein the drain of the third transistor is connected to one terminal of a current source.

### Claim 14 (depends on 13)

The circuit of claim 13 wherein the source of the third transistor is connected to electrical ground.

### Claim 15 (depends on 10)

A current conveyor comprising the circuit of claim 10.

### Claim 16 (depends on 10)

An envelope tracking power amplifier system comprising a power amplifier, wherein the power amplifier comprises the circuit of claim 10.

### Claim 17 (depends on 10)

The circuit of claim 10, wherein the apparatus comprises an amplifier having input terminals coupled to the sources of the first and second transistors and configured to regulate the source voltage of the second transistor.

### Claim 18 (depends on 17)

The circuit of claim 17, wherein the output of the amplifier is coupled to the gate of a third transistor, wherein the drain of the third transistor is coupled to the source of the second transistor, and wherein the output of the amplifier is configured to regulate the source voltage of the second transistor via the third transistor.

### Claim 19 (depends on 10)

The circuit of claim 10, wherein the drain of the first transistor provides the output of the circuit.