Doherty amplifier and communication device

Patent metadata

Field	Value
Publication number	US-2022021345-A1
Application number	US-202117488498-A
Country	US
Kind code	A1
Filing date	Sep 29, 2021
Priority date	Apr 25, 2019
Publication date	Jan 20, 2022
Grant date	—

Abstract

A Doherty amplifier is configured to include a first transistor that amplifies a first signal and outputs the amplified first signal, a second transistor that amplifies a second signal and outputs the amplified second signal, and a combining circuit that combines the amplified first signal output from the first transistor and the amplified second signal output from the second transistor and outputs a combined signal of the amplified first signal and the amplified second signal, in which a signal mode in which the first signal amplified by the first transistor and the second signal amplified by the second transistor are combined in phase and a signal mode in which the first signal amplified by the first transistor and the second signal amplified by the second transistor are combined out of phase are switched in accordance with a frequency, and an operation mode is switched to a Doherty operation mode or an outphasing operation mode depending on the switched signal mode.

First claim

1 . A Doherty amplifier, comprising:
a first transistor that amplifies a first signal and outputs the amplified first signal; a second transistor that amplifies a second signal and outputs the amplified second signal; a combining circuit that combines the amplified first signal output from the first transistor and the amplified second signal output from the second transistor and outputs a combined signal of the amplified first signal and the amplified second signal; and a signal source that switches between a signal mode in which the first signal amplified by the first transistor and the second signal amplified by the second transistor are combined in phase and a signal mode in which the first signal amplified by the first transistor and the second signal amplified by the second transistor are combined out of phase in accordance with a frequency, and wherein an operation mode is switched to a Doherty operation mode or an outphasing operation mode depending on the switched signal mode, wherein an operation mode when an amplitude of the first signal amplified by the first transistor is equal to or larger than an amplitude of the second signal amplified by the second transistor, and a difference between a phase of the first signal amplified by the first transistor and a phase of the second signal amplified by the second transistor is constant is a first Doherty operation mode., and wherein an operation mode when an amplitude of the first signal amplified by the first transistor is the same as an amplitude of the second signal amplified by the second transistor, a phase of the first signal amplified by the first transistor is opposite to a phase of the second signal amplified by the second transistor, and a difference between the phase of the first signal amplified by the first transistor and the phase of the second signal amplified by the second transistor monotonically decreases with an increase in a current of a combined signal output from the combining circuit is a first outphasing operation mode.

2 . The Doherty amplifier according to claim 1 , wherein an operation mode when the signal source generates the first signal and the second signal so that an amplitude of the first signal amplified by the first transistor is the same as an amplitude of the second signal amplified by the second transistor, a phase of the first signal amplified by the first transistor is opposite to a phase of the second signal amplified by the second transistor, and a difference between the phase of the first signal amplified by the first transistor and the phase of the second signal amplified by the second transistor monotonically increases with an increase in a current of a combined signal output from the combining circuit is a second outphasing operation mode.

3 . The Doherty amplifier according to claim 1 , wherein an operation mode when the signal source generates the first signal and the second signal so that an amplitude of the first signal amplified by the first transistor is equal to or less than an amplitude of the second signal amplified by the second transistor, a difference between a phase of the first signal amplified by the first transistor and a phase of the second signal amplified by the second transistor is constant, and a frequency is lower than a frequency in the first Doherty operation mode is a second Doherty operation mode.

4 . The Doherty amplifier according to claim 1 , wherein an operation mode when the signal source generates the first signal and the second signal so that an amplitude of the first signal amplified by the first transistor is equal to or less than an amplitude of the second signal amplified by the second transistor, a difference between a phase of the first signal amplified by the first transistor and a phase of the second signal amplified by the second transistor is constant, and a frequency is higher than a frequency in the first Doherty operation mode is a third Doherty operation mode.

5 . The Doherty amplifier according to claim 1 , wherein
in the first Doherty operation mode,
each of a frequency of the first signal amplified by the first transistor and a frequency of the second signal amplified by the second transistor is a first frequency,
each of an amplitude of the first signal output from the signal source to the input terminal of the first transistor and an amplitude of the second signal output from the signal source to the input terminal of the second transistor monotonically increases with an increase in a voltage of the combined signal output from the combining circuit, and an amplitude of the first signal when an amplitude of the second signal is zero is larger than zero,
an output power of the first transistor is a saturated power when an amplitude of the first signal is maximum, and an output power of the second transistor is a saturated power when an amplitude of the second signal is maximum, and
a phase of the first signal output from the signal source to the input terminal of the first transistor is advanced by 90 degrees from a phase of the second signal output from the signal source to the input terminal of the second transistor.

6 . The Doherty amplifier according to claim 5 , wherein
in the first outphasing operation mode, each of a frequency of the first signal amplified by the first transistor and a frequency of the second signal amplified by the second transistor is a second frequency lower than the first frequency, each of an amplitude of the first signal output from the signal source to the input terminal of the first transistor and an amplitude of the second signal output from the signal source to the input terminal of the second transistor monotonically increases with an increase in a current of a combined signal output from the combining circuit, and the amplitude of the first signal has the same value as the amplitude of the second signal, an output power of the first transistor is a saturated power when the amplitude of the first signal is maximum, and an output power of the second transistor is a saturated power when the amplitude of the second signal is maximum, a phase of the first signal output from the signal source to the input terminal of the first transistor monotonically decreases with an increase in a current of a combined signal output from the combining circuit, a phase of the second signal output from the signal source to the input terminal of the second transistor monotonically increases with an increase in a current of a combined signal output from the combining circuit, and a phase of the first signal and a phase of the second signal are equal in an absolute value and different from each other in a sign.

7 . The Doherty amplifier that switches to the second outphasing operation mode out of the Doherty amplifier according to claim 5 , wherein
in the second outphasing operation mode, each of a frequency of the first signal amplified by the first transistor and a frequency of the second signal amplified by the second transistor is a third frequency higher than the first frequency, each of an amplitude of the first signal output from the signal source to the input terminal of the first transistor and an amplitude of the second signal output from the signal source to the input terminal of the second transistor monotonically increases with an increase in a current of a combined signal output from the combining circuit, and the amplitude of the first signal has the same value as the amplitude of the second signal, an output power of the first transistor is a saturated power when the amplitude of the first signal is maximum, and an output power of the second transistor is a saturated power when the amplitude of the second signal is maximum, a phase of the first signal output from the signal source to the

Assignees

• Mitsubishi Electric Corp

Inventors

• Komatsuzaki Yuji
• Sakata Shuichi
• Shinjo Shintaro
• Otsuka Hiroshi

Classifications

• H04B1/38

  Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving · CPC title

• H03F2200/451

  the amplifier being a radio frequency 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

• H03F2200/222

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

• H03F3/211

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