Patent ID: 9035700
Filing Date: 2015-05-19
Classification: H03F,H03G

Abstract:
1. A variable gain amplifier comprising: an amplifying element including a control terminal to which an input signal is input, a reference-side terminal connected to reference electric-potential, and a power-supply-side terminal connected to a direct-current power supply, the amplifying element configured to amplify the input signal; an FB impedance section connected between the control terminal and the power-supply-side terminal; a reference-side impedance section connected to the reference-side terminal; a power-supply-side impedance section connected to the power-supply-side terminal; a gain controller configured to control a gain of the amplifying element; and a frequency characteristic controller configured to control a frequency characteristic of the gain, wherein the gain controller varies an impedance of one impedance section of the FB impedance section, the reference-side impedance section, and the power-supply-side impedance section, and outputs a control signal for controlling the gain, and the frequency characteristic controller varies an impedance of an impedance section differing from the one impedance section, based on the control signal for controlling the gain.