| 摘要 |
Provided is a small power amplifier capable of suppressing input noise having a differential frequency. A power amplifier (PA1) has an input terminal (IN), an amplifying transistor (11), a bias circuit (21), a filter circuit (61), and an impedance matching circuit (MC1). The bias circuit (21) supplies a bias to a signal input side of the amplifying transistor (11). The filter circuit (61) removes noise of the signal input side of the amplifying transistor (11). The filter circuit (61) has a matching resistor (32), a chip inductor (52), and a chip capacitor (43). Both the chip inductor (52) and the chip capacitor (43) are surface mount devices (SMD). The matching resistor (32) is formed on a semiconductor substrate (1), is connected between a MIM capacitor (42) and a MIM capacitor (41) at one end, and is connected between the MIM capacitor (42) and the signal input side of the amplifying transistor (11) at the other end. |
