Patent ID: 9479117
Filing Date: 2016-10-25
CPC Classification: H03F

Claim Text:
1. A radio-frequency amplifier circuit being a cascode-connected radio-frequency amplifier circuit including first and second field-effect transistors, a gate of the first field-effect transistor serving as an input terminal for a radio-frequency signal, a source of the first field-effect transistor being connected to a ground, a source of the second field-effect transistor being connected to a drain of the first field-effect transistor, a drain of the second field-effect transistor serving as a supply terminal for a drive voltage to be supplied to the first and second field-effect transistors and serving as an output terminal for an amplified radio-frequency signal, the radio-frequency amplifier circuit comprising: a control voltage setting unit that applies a control voltage to a gate of the second field-effect transistor, wherein a transistor size of the first field-effect transistor is the same as a transistor size of the second field-effect transistor, and wherein the control voltage setting unit sets the control voltage so that a voltage at a node between the source of the second field-effect transistor and the drain of the first field-effect transistor is equal to or less than one half of the drive voltage.