JPS6460011A - High frequency transistor amplifier - Google Patents

Abstract

PURPOSE:To reduce energy consumption, by lowering the energy consumption, when a high frequency input signal level is small, compared with the energy consumption, when the said high frequency input signal level is large. CONSTITUTION:A level detecting circuit 3 detects the high frequency signal level inputted to a transistor amplifying circuit 1, and a control circuit 4 changes (controls) the bias output voltage of a power source circuit 2 according to the size of the high frequency signal level detected in the level detecting circuit 3. That is, when the high frequency input signal level is small, since it is needless to enlarge the output performance of the transistor amplifying circuit 1, the bias voltage value is minimized, and the energy consumption is reduced. On the contrary, when the high frequency input signal level is large, since it is required to enlarge the output performance of the transistor amplifying circuit 1, the bias voltage value is enlarged, and the energy consumption is enlarged. Thus, the energy consumption can be reduced.