Patent ID: 8093950
Filing Date: 2012-01-10
Classification: H03F

Abstract:
1. A power amplifier comprising: a first amplifier amplifying a first input signal and a second input signal, which are differential signals; a first coil receiving the first input signal and the second input signal amplified by the first amplifier; a second coil magnetically coupled with the first coil and outputting a composite signal of the amplified first input signal and second input signal; a third coil magnetically coupled with the second coil; a first capacitor coupled between both ends of the third coil; and a semiconductor substrate; wherein one end of the first capacitor is coupled to a ground node; wherein the first coil and the second coil are provided over the main surface of the semiconductor substrate; wherein over the main surface of the semiconductor substrate, there is formed a region with its entire circumference surrounded by the first coil and the second coil; and wherein the third coil is provided in the region.