ULTRAHIGH FREQUENCY AMPLIFIER

摘要

PURPOSE:To decrease a nonlinear distortion and to make the use of an FET efficient by inserting a capacitor short-circuiting a modulation signal between a DC voltage supply line of an amplifier and ground. CONSTITUTION:A QAM wave at an ultrahigh frequency band inputted thereto is outputted via an amplifier FET. In this case, a voltage change is minimized and a capacitor 20 having a value short-circuiting the modulation signal is inserted between a common and a point (a) on a lambdag/4 high impedance line as a point not giving effect on the QAM wave and minimizing the voltage change. Thus, the ternary cross modulation distortion and AM-PM conversion are reduced nearly to half and the FET5 is operated efficiently.