# US 10,771,018 B2 · Harmonic suppression method, corresponding low-noise amplifier, and communication terminal

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- Number: US 10,771,018 B2
- Document ID: US10771018B2
- Status: Granted
- Kind: B2
- Application number: 16/314,369
- Filed: 2017-06-30
- Published: 2019-10-17
- Granted: 2020-09-08
- Earliest claimed: 2016-06-30
- Assignees: Vanchip (Tianjin) Technology Co., Ltd.
- Applicants: Vanchip (Tianjin) Technology Co.,Ltd.
- Inventors: Wenhua Wan
- Web page: https://patentgrep.com/patent/US10771018B2

## CPC

- H03F 1/26: Modifications of amplifiers to reduce influence of noise generated by amplifying elements
- H03F 1/223: {with MOSFET's}
- H03F 1/56: Modifications of input or output impedances, not otherwise provided for
- H03F 1/565: {using inductive elements}
- H03F 3/193: with field-effect devices (H03F3/195 takes precedence)
- H03F 3/195: in integrated circuits
- H03F 3/21: with semiconductor devices only {(H03F3/245 takes precedence)}
- H03F 2200/255: Amplifier input adaptation especially for transmission line coupling purposes, e.g. impedance adaptation
- H03F 2200/267: A capacitor based passive circuit, e.g. filter, being used in an amplifying circuit
- H03F 2200/294: the amplifier being a low noise amplifier [LNA]
- H03F 2200/372: Noise reduction and elimination in amplifier
- H03F 2200/451: the amplifier being a radio frequency amplifier
- H03F: AMPLIFIERS

## Abstract

Provided is a harmonic suppression method, a corresponding low-noise amplifier (20, 30, 40), and a communication terminal. In the harmonic suppression method, an isolation unit (23, 33, 43) is arranged between a harmonic suppression unit (24, 34, 44) of the low-noise amplifier (20, 30, 40) and an output match network (25, 35, 45)/input match network (21, 31, 41). The harmonic suppression unit (24, 34, 44) is isolated from the output match network (25, 35, 45)/input match network (21, 31, 41) by means of the isolation unit (23, 33, 43), so that the two are not affected or compromised by each other, and can be designed separately. In this way, the design flexibility of a signal amplification circuit is greatly improved, and the design difficulty is reduced.

## Claims

### Claim 1

A low-noise amplifier, wherein an isolation unit is arranged between a harmonic suppression unit and an output match network/input match network, the isolation unit comprises one or more transistors;
the low-noise amplifier further comprising an input bias resistor and an output bias inductor;
wherein one end of the input bias resistor is connected to a direct current working point control end of the amplification unit, and the other end of the input bias resistor is connected to a direct current bias signal, to implement high-impedance isolation of the direct current bias signal from a radio frequency signal; and
the output bias inductor is connected between a power supply and the output match network and configured to provide a direct current bias point to the low-noise amplifier.

### Claim 2 (depends on 1)

The low-noise amplifier according to claim 1, further comprising an amplification unit, wherein
the amplification unit is connected between the input match network and the harmonic suppression unit, one end of the harmonic suppression unit is connected to the amplification unit, the other end of the harmonic suppression unit is connected to the isolation unit, and the isolation unit is connected between the harmonic suppression unit and the output match network.

### Claim 3 (depends on 1)

The low-noise amplifier according to claim 1, wherein in the amplification unit, the direct current working point control end and a signal input end are a same end.

### Claim 4 (depends on 1)

The low-noise amplifier according to claim 1, wherein the harmonic suppression unit has one or more harmonic frequency resonant points expected to be suppressed.

### Claim 5 (depends on 1)

The low-noise amplifier according to claim 1, wherein the harmonic suppression unit is an LC parallel resonant circuit, one end of the LC parallel resonant circuit is connected to an output end of the amplification unit, and the other end of the LC parallel resonant circuit is connected to an input end of the isolation unit.

### Claim 6 (depends on 1)

The low-noise amplifier according to claim 1, further comprising an isolation unit bias resistor, wherein one end of the isolation unit bias resistor is connected to a direct current working point control end of the isolation unit, and the other end of the isolation unit bias resistor is connected to a direct current bias signal.

### Claim 7 (depends on 1)

The low-noise amplifier according to claim 1, further comprising a direct current blocking capacitor, wherein one polar plate of the direct current blocking capacitor is connected to one end of a resonant inductor, the other polar plate of the direct current blocking capacitor is connected to alternating current ground, and the other end of the resonant inductor is connected to a control end of the isolation unit, so that the direct current blocking capacitor, the resonant inductor, and a parasitic capacitor in the isolation unit form an LC series resonant circuit.

### Claim 8 (depends on 1)

The low-noise amplifier according to claim 1, wherein the harmonic suppression unit is an LC series resonant circuit, one end of the LC series resonant circuit is connected to an output end of the amplification unit and is connected to an input end of the isolation unit, and the other end of the LC series resonant circuit is connected to alternating current ground.

### Claim 9 (depends on 1)

A communication terminal, comprising a signal amplification circuit, wherein the signal amplification circuit uses the low-noise amplifier according to claim 1.