Doherty amplifier

Patent metadata

Field	Value
Publication number	US-12512791-B2
Application number	US-202217893316-A
Country	US
Kind code	B2
Filing date	Aug 23, 2022
Priority date	Apr 27, 2020
Publication date	Dec 30, 2025
Grant date	Dec 30, 2025

Abstract

A Doherty amplifier includes: a first amplifying element to amplify a first signal; a second amplifying element to amplify a second signal having a phase difference with the first signal; a first transmission line connected to an output terminal of the first amplifying element; and a second transmission line connected to an output terminal of the second amplifying element, wherein the first transmission line and the second transmission line are equal to each other in characteristic impedance, the phase difference between the first signal and the second signal is not equal to a difference in electrical length between the second transmission line and the first transmission line, and the first signal having passed through the first transmission line and the second signal having passed through the second transmission line are subjected to different phase synthesis.

First claim

What is claimed is:

1 . A Doherty amplifier comprising:
a first amplifying element to amplify a first signal; a second amplifying element to amplify a second signal having a phase difference with the first signal; a first transmission line connected to an output terminal of the first amplifying element; and a second transmission line connected to an output terminal of the second amplifying element, wherein the first transmission line and the second transmission line are equal to each other in characteristic impedance, the phase difference between the first signal and the second signal is not equal to a difference in electrical length between the second transmission line and the first transmission line, the phase difference between the first signal and the second signal being constant regardless of input power levels of the first amplifying element and the second amplifying element, the first signal having passed through the first transmission line and the second signal having passed through the second transmission line are subjected to different phase synthesis, the electrical length of the first transmission line is within a range from 70 degrees to 90 degrees, the electrical length of the second transmission line is within a range from 90 degrees to 180 degrees, and each of respective values of the characteristic impedance of the first transmission line and the characteristic impedance of the second transmission line is smaller than double the value of a resistance of an external load.

2 . The Doherty amplifier according to claim 1 , wherein
a ratio of a voltage amplitude of the first signal input to the first amplifying element and a voltage amplitude of the second signal input to the second amplifying element is controlled in order that the voltage amplitude of the second signal input to the second amplifying element is 0 when the voltage amplitude of the first signal input to the first amplifying element is equal to or less than a threshold, and rises when the voltage amplitude of the first signal input to the first amplifying element is larger than the threshold.

3 . The Doherty amplifier according to claim 2 , wherein
the ratio of the voltage amplitude of the first signal to the voltage amplitude of the second signal approaches asymptotically 1 with an increase in output power levels of the first amplifying element and the second amplifying element.

4 . The Doherty amplifier according to claim 2 , wherein
the phase difference between the first signal and the second signal has a value having a variation in a range of ±20%.

5 . The Doherty amplifier according to claim 1 , wherein
a phase difference between a signal output from the first amplifying element and a signal output from the second amplifying element is constant regardless of input power levels of the first amplifying element and the second amplifying element.

6 . The Doherty amplifier according to claim 1 , further comprising:
a divider circuit to divide an input signal; a first phase adjustment line to generate a first delay for the signal divided by the divider circuit; and a second phase adjustment line to further generate a second delay for the signal having passed through the first phase adjustment line, wherein a sum of passing phases of the first phase adjustment line and the second phase adjustment line is equal to the phase difference between the first signal and the second signal.

7 . The Doherty amplifier according to claim 1 , wherein the phase difference between the first signal and the second signal is larger than a difference in electrical length between the second transmission line and the first transmission line.

8 . The Doherty amplifier according to claim 6 , wherein
the phase difference between the first signal and the second signal is larger than a difference in electrical length between the second transmission line and the first transmission line.

9 . The Doherty amplifier according to claim 1 , wherein
the phase difference between the first signal and the second signal is smaller than a difference in electrical length between the second transmission line and the first transmission line.

10 . The Doherty amplifier according to claim 6 , wherein
the phase difference between the first signal and the second signal is smaller than a difference in electrical length between the second transmission line and the first transmission line.

11 . The Doherty amplifier according to claim 1 , wherein
a phase difference between the second signal input to the second amplifying element and the first signal input to the first amplifying element is within a range from 45 degrees to 90 degrees.

12 . A Doherty amplifier comprising:
a first amplifying element to amplify a first signal; a second amplifying element to amplify a second signal having a phase difference with the first signal; a first transmission line connected to an output terminal of the first amplifying element; and a second transmission line connected to an output terminal of the second amplifying element, an output combining point for connecting the Doherty amplifier to an external load at which the first signal having passed through the first transmission line and the second signal having passed through the second transmission line are subjected to different phase synthesis and combined for direct outputting to the external load, wherein the first transmission line and the second transmission line are equal to each other in characteristic impedance, the phase difference between the first signal and the second signal is configured to be selected so as not to be equal to a difference in electrical length between the second transmission line and the first transmission line, the electrical length of the first transmission line is within a range from 70 degrees to 90 degrees, the electrical length of the second transmission line is within a range from 90 degrees to 180 degrees, and the characteristic impedance of the first transmission line and the characteristic impedance of the second transmission line are smaller than a value obtained by doubling the external load.

13 . The Doherty amplifier according to claim 12 , wherein
a ratio of a voltage amplitude of the first signal input to the first amplifying element and a voltage amplitude of the second signal input to the second amplifying element is controlled in order that the voltage amplitude of the second signal input to the second amplifying element is 0 when the voltage amplitude of the first signal input to the first amplifying element is equal to or less than a threshold, and rises when the voltage amplitude of the first signal input to the first amplifying element is larger than the threshold.

14 . The Doherty amplifier according to claim 13 , wherein
the ratio of the voltage amplitude of the first signal to the voltage amplitude of the second signal approaches asymptotically 1 with an increase in output power levels of the first amplifying element and the second amplifying element.

15 . The Doherty amplifier according to claim 13 , wherein
the phase difference between the first signal and the second signal has a value having a variation in a range of ±20%.

16 . The Doherty amplifier according to claim 12 , wherein
a phase difference between a signal output from the first amplifying element and a signal output from the second amplifying element is constant regardless of input power levels of the first amplifying element and the second amplifying element.

17 . The Doherty amplifier according to claim 12

Assignees

• Mitsubishi Electric Corp

Inventors

• Torii Takuma
• Komatsuzaki Yuji
• Shinjo Shintaro

Classifications

• H03F2200/451

  the amplifier being a radio frequency amplifier · CPC title

• H03F3/211

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

• H03F3/602

  Combinations of several amplifiers · CPC title

• H03F2200/255

  Amplifier input adaptation especially for transmission line coupling purposes, e.g. impedance adaptation · CPC title

• H03F2200/315

  the loading circuit of an amplifying stage comprising a transmission line · CPC title