Power amplifier with termination circuit and resonant circuit

Patent metadata

Field	Value
Publication number	US-2016013758-A1
Application number	US-201514671079-A
Country	US
Kind code	A1
Filing date	Mar 27, 2015
Priority date	Jul 11, 2014
Publication date	Jan 14, 2016
Grant date	—

Abstract

Aspects of this disclosure relate to efficient power amplifiers, such as class-F power amplifiers. A power amplifier transistor can provide an amplified RF signal. A termination can be coupled to an output of the power amplifier transistor and configured to provide a short circuit at a second harmonic. In some instances, the termination circuit can provide an open circuit at a third harmonic. A resonant circuit can be coupled to the output terminal of the power amplifier transistor and configured to provide an open circuit at the third harmonic. In certain embodiments, an input termination circuit coupled to an input terminal of the power amplifier transistor can provide a short circuit at the second harmonic. The power amplifiers of this disclosure can be implemented, for example, in envelope tracking applications.

First claim

What is claimed is:

1 . An apparatus comprising:
a power amplifier transistor configured to receive a radio frequency (RF) signal at an input terminal and provide an amplified RF signal at an output terminal; an input termination circuit coupled to the input terminal of the power amplifier transistor, the input termination circuit configured to provide a short circuit at a second harmonic of the RF signal; a termination circuit coupled to the output terminal of the power amplifier transistor, the termination circuit configured to provide a short circuit at a second harmonic of the amplified RF signal; and a resonant circuit coupled to the output of the power amplifier transistor, the resonant circuit configured to provide an open circuit at a third harmonic of the amplified RF signal.

2 . The apparatus of claim 1 wherein the termination circuit is configured to provide an open circuit at the third harmonic of the amplified RF signal.

3 . The apparatus of claim 1 further comprising an envelope tracking modulator and a parallel LC circuit disposed between the envelope tracking modulator and the output terminal of the power amplifier transistor, the envelope tracking modulator configured to provide a supply voltage to the power amplifier transistor by way of the parallel LC circuit.

4 . The apparatus of claim 3 wherein the parallel LC circuit is configured to block a fundamental frequency of the amplified RF signal.

5 . The apparatus of claim 1 wherein the power amplifier transistor includes a bipolar transistor having a collector, a base, and an emitter, the input terminal of the power amplifier transistor being the base, and the output terminal of the power amplifier transistor being the collector.

6 . The apparatus of claim 1 wherein the power amplifier transistor is implemented on a power amplifier die, and the input termination circuit includes an inductive element external to the power amplifier die.

7 . The apparatus of claim 1 wherein the termination circuit is configured to provide a short circuit at a different even harmonic of the amplified RF signal.

8 . The apparatus of claim 7 wherein the power amplifier transistor is implemented on a power amplifier die, termination circuit includes a first LC circuit configured to provide the short circuit at the second harmonic of the amplified RF signal and a second LC circuit configured to provide the short circuit at the different even harmonic of the amplified RF signal, the first LC circuit including a first inductive element external to the power amplifier die, and the second LC circuit including a second inductive element external to the power amplifier die.

9 . The apparatus of claim 1 wherein the resonant circuit is configured to provide an open circuit at another odd harmonic of the amplified RF signal.

10 . The apparatus of claim 1 wherein the termination circuit includes a capacitor in parallel with a series LC circuit.

11 . The apparatus of claim 1 wherein the resonant circuit includes a parallel LC circuit.

12 . An apparatus comprising:
a bipolar power amplifier transistor having a collector, a base, and an emitter, the bipolar power amplifier transistor configured to amplify a radio frequency (RF) signal received at the base, and the bipolar power amplifier transistor being implemented on a power amplifier die; a termination circuit coupled to the collector of the bipolar power amplifier transistor, the termination circuit including a capacitor in parallel with a series LC circuit, the series LC circuit including an inductive element external to the power amplifier die; and a parallel LC circuit coupled in series between the collector and a load.

13 . The apparatus of claim 12 wherein the bipolar power amplifier transistor, the termination circuit, and the parallel LC circuit are arranged as a class F power amplifier.

14 . The apparatus of claim 12 further comprising a second series LC circuit coupled to the base of the power amplifier transistor.

15 . The apparatus of claim 12 further comprising an envelope tracking modulator configured to provide a supply voltage for the collector of the bipolar power amplifier transistor.

16 . The apparatus of claim 15 further comprising a second parallel LC circuit disposed between the envelope tracking modulator and the collector, the envelope tracking modulator configured to provide the supply voltage to the collector by way of the second parallel LC circuit.

17 . The apparatus of claim 12 wherein the termination circuit includes a second series LC circuit in parallel with the series LC circuit, the second series LC circuit including the capacitor.

18 . A power amplifier module comprising:
a power amplifier transistor configured to receive a radio frequency (RF) input signal and provide an amplified RF signal; a termination circuit coupled to an output of the power amplifier transistor, the termination circuit configured to provide a short circuit at a second harmonic of the amplified RF signal and an open circuit at a third harmonic of the amplified RF signal; a resonant circuit coupled to the output of the power amplifier transistor, the resonant circuit configured to provide an open circuit at the third harmonic of the amplified RF signal; and a supply voltage circuit including an envelope tracking modulator and a parallel LC circuit disposed between the envelope tracking modulator and the power amplifier transistor, the envelope tracking modulator configured to provide a supply voltage to the power amplifier transistor by way of the parallel LC circuit.

19 . The power amplifier module of claim 18 further comprising an input termination circuit configured to provide a short circuit at a second harmonic of the RF input signal, the input termination circuit being coupled to an input of the power amplifier transistor.

20 . The power amplifier module of claim 18 wherein the power amplifier transistor includes a heterojunction bipolar transistor.

Assignees

• Skyworks Solutions Inc

Inventors

• Cao Haibo
• Wu Andy Cheng Pang
• Lin Yu-Jui
• King Joel Richard

Classifications

• H03F2200/451

  the amplifier being a radio frequency amplifier · CPC title

• H03F3/19

  with semiconductor devices only · CPC title

• H03F1/0222 Primary

  by using a signal derived from the input signal · CPC title

• H03F3/21

  with semiconductor devices only {(H03F3/245 takes precedence)} · CPC title

• H03F1/565

  using inductive elements · CPC title