US 2024/0204731 A1 · DOHERTY AMPLIFIER

Abstract

A Doherty amplifier including: a first transistor for main amplifier having a source-to-drain parasitic capacitance and operating in class AB; a transmission line whose input end is connected to an output end of the first transistor and whose output end is connected to a composite point; a second transistor for auxiliary amplifier having a source-to-drain parasitic capacitance and operating in class C; a series capacitor whose input end is connected to an output end of the second transistor and whose output end is connected to the composite point, and to reduce the capacitance value of impedance seen from the composite point toward the output end of the second transistor at the time of a backoff operation; and an output matching circuit connected between the composite point and a point of connection to an output load, to match the impedance of the composite point to the impedance of the output load.

Claims4

Dependent claims

A Doherty amplifier comprising:

a transistor for main amplifier having a source-to-drain parasitic capacitance and operating in class AB;
a transmission line whose input end is connected to an output end of the transistor for main amplifier and whose output end is connected to a composite point;
a transistor for auxiliary amplifier having a source-to-drain parasitic capacitance and operating in class C;
a series capacitor whose input end is connected to an output end of the transistor for auxiliary amplifier and whose output end is connected to the composite point, and to reduce a capacitance value of impedance seen from the composite point toward the output end of the transistor for auxiliary amplifier at a time of a backoff operation;
and
an output matching circuit connected between the composite point and a point of connection to an output load, and to match impedance at the composite point to impedance of the output load.

3 more elements

A Doherty amplifier comprising:

a transistor for main amplifier having a source-to-drain parasitic capacitance and operating in class AB;
a transmission line whose input end is connected to an output end of the transistor for main amplifier and whose output end is connected to a composite point;
a transistor for auxiliary amplifier having a source-to-drain parasitic capacitance and operating in class C;
a series capacitor whose input end is connected to an output end of the transistor for auxiliary amplifier and whose output end is connected to the composite point;
and
an output matching circuit connected between the composite point and a point of connection to an output load, and to match impedance of the composite point to impedance of the output load,
wherein a virtual parallel capacitor connected to the output end of the transmission line and a virtual parallel inductor connected to the output end of the series capacitor and resonating with the virtual parallel capacitor are inherent in the Doherty amplifier, and at a time of a backoff operation, the source-to-drain parasitic capacitance of the transistor for main amplifier, the transmission line, and the virtual parallel capacitor constitute a transmission line having an F matrix equivalent to that of a transmission line whose characteristic impedance is larger than impedance of an optimal load of the transistor for main amplifier and whose electric length is shorter than 90 degrees.

4 more elements

Dependencies are inferred from the claim text.

Doherty amplifier

Life of this patent

Doherty amplifier

Life of this patent

Abstract

Claims4