Doherty power amplifier with integrated second harmonic injection

Patent metadata

Field	Value
Publication number	US-10972053-B2
Application number	US-201916407108-A
Country	US
Kind code	B2
Filing date	May 8, 2019
Priority date	May 8, 2018
Publication date	Apr 6, 2021
Grant date	Apr 6, 2021

Abstract

Examples disclosed herein relate to a Doherty Power Amplifier (“DPA”) with integrated second harmonic injection. The DPA includes an amplifier circuit having a carrier amplifier and a peaking amplifier, and a combiner network coupled to the amplifier circuit, the combiner network having a plurality of transmission lines and a LC resonant circuit to inject a second harmonic from the carrier amplifier into the peaking amplifier.

First claim

What is claimed is:

1. A Doherty Power Amplifier (“DPA”) with integrated second harmonic injection, comprising:
an amplifier circuit comprising a carrier amplifier and a peaking amplifier; and
a combiner network coupled to the amplifier circuit, the combiner network having a plurality of transmission lines and a LC resonant circuit to inject a second harmonic from the carrier amplifier into the peaking amplifier, wherein the plurality of transmission lines comprises at least one λ/8 transmission line in parallel with the LC resonant circuit.

2. The DPA of claim 1 , wherein the amplifier circuit further comprises a splitter to split an RF input signal into a first and a second signal 90° out of phase, the first signal input into the carrier amplifier and the second signal input into the peaking amplifier.

3. The DPA of claim 1 , wherein the plurality of transmission lines further comprises a first λ/4 transmission line in parallel with the LC resonant circuit.

4. The DPA of claim 1 , wherein a transmission line in the plurality of transmission lines comprises an impedance transformer with a first and a second varactor in parallel.

5. The DPA of claim 1 , wherein the LC resonant circuit comprises an open circuit at a fundamental frequency.

6. The DPA of claim 1 , wherein the LC resonant circuit comprises a short circuit at a second harmonic.

7. The DPA of claim 3 , wherein the first λ/4 transmission line couples an output of the carrier amplifier to an output of the peaking amplifier.

8. The DPA of claim 3 , wherein the first λ/4 transmission line provides a 90° phase shift.

9. The DPA of claim 1 , wherein the second harmonic signal from the carrier amplifier is injected at an output of the peaking amplifier at back-off.

10. A combiner network to increase the efficiency of a Doherty Power Amplifier (“DPA”) for use in millimeter wave applications, the combiner network comprising:
a first λ/4 transmission line coupled to a carrier amplifier and a peaking amplifier;
a second λ/8 transmission line coupled to the first λ/4 transmission line;
a third λ/8 transmission line coupled to the second λ/8 transmission line; and
an LC resonant circuit in parallel with the second and third λ/8 transmission lines, wherein one of the first λ/4 transmission line, the second λ/8 transmission line, or the third λ/8 transmission line comprises an impedance transformer with a first and a second varactor in parallel.

11. The combiner network of claim 10 , wherein the carrier amplifier and the peaking amplifier are coupled to a splitter.

12. The combiner network of claim 11 , wherein the splitter is to split an RF input signal into a first and a second signal, the first signal input into the carrier amplifier and the second signal input into the peaking amplifier.

13. The combiner network of claim 11 , further comprising a fourth λ/4 transmission line coupled between the splitter and the peaking amplifier.

14. The combiner network of claim 10 , wherein the LC resonant circuit comprises a series LC resonant circuit coupled to a parallel LC resonant circuit.

15. The combiner network of claim 10 , wherein the LC resonant circuit comprises an open circuit at a fundamental frequency and a short circuit at the second harmonic.

16. The combiner network of claim 10 , wherein the third λ/8 transmission line is coupled to a load.

17. A method to increase the efficiency of a Doherty Power Amplifier (“DPA”) for use in millimeter wave applications, the method comprising:
providing an amplifier circuit with a carrier amplifier and a peaking amplifier;
coupling a combiner network to the amplifier circuit via a transmission line comprising an impedance transformer with a first and a second varactor in parallel; and
injecting a second harmonic from the carrier amplifier into the peaking amplifier at back-off to increase a back-off efficiency of the peaking amplifier.

18. The method of claim 17 , wherein coupling the combiner network to the amplifier circuit comprises coupling a first λ/4 transmission line to the carrier amplifier and the peaking amplifier.

19. The method of claim 18 , wherein coupling the combiner network to the amplifier circuit further comprises coupling the first λ/4 transmission line to an LC resonant circuit in parallel with a second and a third λ/8 transmission lines.

20. The method of claim 17 , wherein injecting a second harmonic comprises injecting the second harmonic into the peaking amplifier during isolation from a load.

Assignees

• Metawave Corp

Inventors

• Dani Asmita

Classifications

• H03F2200/171

  A filter circuit coupled to the output of an amplifier · CPC title

• H03F2200/387

  A circuit being added at the output of an amplifier to adapt the output impedance of the amplifier · CPC title

• H03F2203/21106

  An input signal being distributed in parallel over the inputs of a plurality of power amplifiers · CPC title

• H03F2203/21157

  A filter circuit being added at the output of a power amplifier stage · CPC title

• H03F1/0288 Primary

  using a main and one or several auxiliary peaking amplifiers whereby the load is connected to the main amplifier using an impedance inverter, e.g. Doherty amplifiers · CPC title