US 12,407,308 B2
Radio-frequency circuit and communication device
Masakazu Hirobe, Kyoto (JP)
Assigned to MURATA MANUFACTURING CO., LTD., Kyoto (JP)
Filed by Murata Manufacturing Co., Ltd., Kyoto (JP)
Filed on Nov. 14, 2022, as Appl. No. 18/054,933.
Application 18/054,933 is a continuation of application No. PCT/JP2021/016502, filed on Apr. 23, 2021.
Claims priority of application No. 2020-106479 (JP), filed on Jun. 19, 2020.
Prior Publication US 2023/0073635 A1, Mar. 9, 2023
Int. Cl. H03F 3/191 (2006.01); H03F 3/24 (2006.01)
CPC H03F 3/245 (2013.01) [H03F 2200/24 (2013.01); H03F 2200/451 (2013.01); H03F 2200/78 (2013.01)] 13 Claims
OG exemplary drawing
 
1. A radio-frequency circuit comprising:
an amplifier circuit comprising a specific transistor that has an input terminal and an output terminal, and that is configured to amplify a radio-frequency signal input to the input terminal and to output an amplified radio-frequency signal from the output terminal;
a bias circuit configured to supply a bias current or a bias voltage to the input terminal of the specific transistor;
a bias control circuit configured to supply a control current or a control voltage to the bias circuit;
comparing circuitry configured to compare a threshold voltage with a power supply voltage of a power supply terminal connected to the output terminal of the specific transistor;
a signal input terminal connected to the input terminal of the specific transistor, and to which the radio-frequency signal is input;
an antenna terminal;
an attenuation circuit connected in a signal path between the signal input terminal and the antenna terminal, and configured to attenuate the radio-frequency signal; and
control circuitry configured to change an attenuation of the attenuation circuit in accordance with a result of the comparing section.