Patent ID: 9407222
Filing Date: 2016-08-02
CPC Classification: H03F,H03G

Claim Text:
1. An amplifier comprising: a first transistor circuit which amplifies a high frequency signal; a second transistor circuit which amplifies the high frequency signal amplified by the first transistor circuit; a first DC potential transmission circuit which applies a DC control voltage to an input terminal of the first transistor circuit; a second DC potential transmission circuit which applies a DC power source voltage to an output terminal of the second transistor circuit; a transformer which is disposed between the respective first and second transistor circuits, wherein a primary inductor device and a secondary inductor device are magnetically coupled in the transformer; a first capacitive element; a second capacitive element; and a choke coil which passes the DC power source voltage of the first transistor circuit between the primary inductor device and a bias circuit for the first transistor circuit, wherein the primary inductor device is connected between an output terminal of the first transistor circuit and the bias circuit for the first transistor circuit, the secondary inductor device is connected between an input terminal of the second transistor circuit and a bias circuit for the second transistor circuit, a connection point between the primary inductor device and the bias circuit for the first transistor circuit is connected to the first capacitive element, a connection point between the secondary inductor device and the bias circuit for the second transistor circuit is connected to the second capacitive element, and at least one of inductance values of the respective primary and secondary inductor devices and capacitance values of the respective first and second capacitive elements is variable.