Impedance circuit, and filter circuit, amplifier circuit, semiconductor integrated circuit, electronic component, and wireless communications device using the same

摘要

A filter circuit is provided wherein one end of an inductor is connected to one end of a capacitor to form a signal input end. The other end of the inductor is connected to a first switch circuit, and the other end of the capacitor is connected to a second switch circuit. When a lower-frequency signal in a 2.4 GHz band is to be inputted, a low-pass filter circuit is formed by connecting the other end of the inductor to a signal output end and the other end of the capacitor to ground, and when a higher-frequency signal in a 5 GHz band is to be inputted, a high-pass filter circuit is formed by connecting the other end of the inductor to ground and the other end of the capacitor to the signal output end, by manipulating the first and second switch circuits.