Power amplification circuit

A power amplification circuit comprising a field-effect transistor for amplifying the power of an input high-frequency signal and an input matching circuit connected between a signal source and said field-effect transistor,

• said field-effect transistor comprising:
• an active layer formed on a (1 0 0)-crystal plane of a compound semiconductor substrate;
• a source electrode and a drain electrode, each of said source and drain electrodes forming an ohmic junction with said active layer;
• and
• a gate electrode which forms a Schottky junction with said active layer and is connected to said input matching circuit;
• wherein:
• an angle .theta., formed between the longitudinal axial direction of said gate electrode and the <0 -1 -1>-direction of said compound semiconductor substrate, is set so as to fall in the range from 0.degree. to 90.degree. in order that a temperature coefficient of the input impedance real part of said field-effect transistor becomes substantially equal to a temperature coefficient of the output impedance real part of said input matching circuit.