Wideband amplifier

Patent metadata

Field	Value
Publication number	US-9362871-B2
Application number	US-201414444106-A
Country	US
Kind code	B2
Filing date	Jul 28, 2014
Priority date	Aug 30, 2013
Publication date	Jun 7, 2016
Grant date	Jun 7, 2016

Abstract

A Doherty amplifier is disclosed, being adapted to receive an RF input signal and to output an RF output signal and comprising a main amplifier and a peak amplifier, each comprising: a first amplifier (T 1 , T 1 ′) and a second amplifier (T 2 , T 2 ′), each amplifier having a respective input terminal and a respective output terminal, the first amplifier and the second amplifier being adapted to amplify a respective input signal derived from the RF input signal and received at the respective input terminal and to deliver a first output signal and a second output signal, respectively; a first phase shifter ( 14, 14 ′) and a second phase shifter ( 15, 15 ′) coupled to the output terminal of the first amplifier and to the output terminal of the second amplifier, respectively; a third phase shifter ( 16, 16 ′); and a fourth phase shifter ( 17, 17 ′); wherein the Doherty amplifier further comprises a first combining node (A) and a second combining node (B) and, wherein each third phase shifter is coupled between the respective first phase shifter and the first combining node; each fourth phase shifter is coupled between the respective second phase shifter and the second combining node, and the third phase shifter of each of the main amplifier and the peak amplifier is adapted to be electrically coupled to the respective fourth phase shifter the output RF signal being obtained from a signal obtained in the first combining node and a signal obtained in the second combining node. An associated PCB is also disclosed.

First claim

The invention claimed is:

1. A Doherty amplifier, comprising:
an RF signal input;
an RF signal output;
a main amplifier portion and a peak amplifier portion,
wherein the main and peak amplifiers portions each include:
a first amplifier;
a second amplifier,
a first phase shifter;
a second phase shifter;
a third phase shifter;
a fourth phase shifter;

wherein the first and second amplifiers each include an input terminal coupled to the RF signal input and an output terminal,
wherein within each of the portions,
the first phase shifter is coupled to the output terminal of the first amplifier
the second phase shifter is coupled to the output terminal of the second amplifier;
the third phase shifter is coupled to the first phase shifter; and
the fourth phase shifter coupled to the second phase shifter;

wherein the Doherty amplifier further comprises a first combining node and a second combining node,
wherein each portion's third phase shifter is coupled to the first combining node;
wherein each portion's fourth phase shifter is coupled to the second combining node, and
wherein the RF signal output is coupled to the first combining node and the second combining node.

2. A Doherty amplifier as claimed in claim 1 ,
wherein the first amplifier and the second amplifier each comprises a differential pair of transistors.

3. A Doherty amplifier as claimed in claim 1 ,
wherein each portion's third phase shifter is electrically coupled to each portion's fourth phase shifter; and
wherein the electrical coupling between each third phase shifter and the respective fourth phase shifter is adapted to reduce a harmonic component on the output terminals of the first and second amplifiers.

4. A Doherty amplifier as claimed in claim 1 ,
wherein any of the first phase shifter, the second phase shifter, the third phase shifter and the fourth phase shifter is adapted to be implemented as a strip line.

5. A Doherty amplifier as claimed in claim 1 , wherein
a sum of a phase shift of the first phase shifter and a phase shift of the third phase shifter of the first amplifier is substantially 90°;
a sum of a phase shift of the second phase shifter and a phase shift of the fourth phase shifter of the first amplifier is substantially 90°;
a sum of a phase shift of the first phase shifter and a phase shift of the third phase shifter of the second amplifier is substantially 180°; and
a sum of a phase shift of the second phase shifter and a phase shift of the fourth phase shifter of the second amplifier is substantially 180°.

6. A Doherty amplifier as claimed in claim 1 further comprising:
a first balun;
a first string of serially coupled transmission lines having a first end coupled to the first combining point and a second end coupled to a first terminal of the balun;
a second string of serially coupled transmission lines having a third end coupled to the second combining point and a fourth end coupled to a second terminal of the balun;
a third terminal of the balun configured to be coupled to a load impedance;
a fourth terminal of the balun configured to be coupled to a ground terminal; and wherein
each transmission line included in the first string of serially coupled transmission lines is adapted to be electrically coupled to a respective transmission line included in the second string of the serially coupled transmission lines.

7. A Doherty amplifier as claimed in claim 1 further comprising a capacitor coupled to the first combining point and to the second combining point.

8. A Doherty amplifier as claimed in claim 1 further comprising
a second balun;
a third balun;
each of the second and third balun comprising a respective input terminal and first and second output terminals,
the input terminal of the second balun adapted to receive an RF input signal on the RF signal input, the input terminal of the third balun adapted to receive a phase shifted version of the RF input signal, the first and the second output terminal of the second balun coupled to the respective input terminals of the first amplifier and the second amplifier included in the main amplifier, and the first and the second output terminal of the third balun coupled to the respective input terminals of the first amplifier and the second amplifier included in the peak amplifier.

9. A Doherty amplifier as claimed in claim 8 , further comprising
a signal splitter comprising a splitter input terminal, a first splitter output terminal and a second splitter output terminal,
the first splitter output terminal coupled to the input terminal of the second balun and the second splitter output terminal coupled to the input terminal of the third balun.

10. A Doherty amplifier as claimed in claim 9 ,
wherein one of the first splitter output terminal or the second splitter output terminal is coupled to a phase compensator,
the phase compensator coupled to either the input terminal of the second balun, or to the input terminal of the third balun.

11. A printed circuit board comprising
a first copper covered surface,
wherein at least a subset of the phase shifters and a subset of the transmission lines included in a Doherty amplifier as claimed in claim 1 are implemented as strip lines in the first copper covered surface.

12. A printed circuit board as claimed in claim 11 further comprising
a second copper covered surface opposing the first copper covered surface, wherein:
the first copper covered surface is adapted to accommodate a first structure comprising the third phase shifters and the first string of serially coupled transmission lines, the first structure having a first shape, a first orientation and a first position;
the second copper covered surface is adapted to accommodate a second structure comprising the fourth phase shifters and the second string of serially coupled transmission lines, the second structure having a second shape, a second orientation and a second position; and
wherein the first structure is a mirrored version of the second structure.

13. A power module comprising a Doherty amplifier mounted on a printed circuit board as claimed in claim 11 .

Assignees

• Ampleon Netherlands Bv

Inventors

• Qureshi Jawad Hussain

Classifications

• H03F3/211 Primary

  using a combination of several amplifiers (H03F3/60 takes precedence) · CPC title

• H03F2200/204

  A hybrid coupler being used at the output of an amplifier circuit · CPC title

• H03F3/604

  using FET's · CPC title

• H03F2200/198

  A hybrid coupler being used as coupling circuit between stages of an amplifier circuit · CPC title

• H01P5/187

  Broadside coupled lines · CPC title