Power amplifier

Abstract

In the power amplifier of the invention, at a start of power amplification by an amplifier transistor 103 serving as an amplification section, a speedup circuit 122 transiently increases a bias which is fed to the amplifier transistor 103 via a bias power source section composed of a bias circuit 111 and a power source circuit 112. As a result, the power amplification factor of the amplifier transistor 103 is transiently increased at the start of power amplification by the amplifier transistor 103. Thus, the time elapsing until temperature variations due to heat generation of the amplifier transistor 103 come to an equilibrium on the whole circuit is shortened, with a result of reduced distortion of the amplification signal such as a modulated-wave signal. Accordingly, in the invention, it becomes possible to suppress distortion increases of an amplification signal due to heat generation at the start time without using any temperature sensing element.

Dependencies are inferred from the claim text.