SEMICONDUCTOR AMPLIFIER

PROBLEM TO BE SOLVED: To provide a multi-stage semiconductor amplifier which can suppress an output increase during low temperature in an amplification section operating in a saturation region, or a change in power consumption or harmonic frequency or the like owing to a change in output impedance. SOLUTION: The semiconductor amplifier includes: a first amplifying element 1a which is provided at a final-stage amplification section 1 for outputting high-frequency power and amplifies power of a microwave band to a saturated output power; a second amplifying element 2a which is provided at a preamplification section 2 placed before the first amplifying element 1a and amplifies high-frequency power; a temperature compensation circuit 5 which is connected with the second amplifying element 2a and changes the output power of the second amplifying element 2a by a change in resistance value of a thermosensitive element; and an amplitude equalizer 4 which is interposed between the input side of the first amplifying element 1a and the output side of the second amplifying element 2a and has a pass amplitude characteristics to maximize attenuation at the center frequency region of a microwave band by a change in resonance impedance. Thus, the output of the first amplifying element 1a can be kept in the saturated output power range by reducing the output power of the second amplifying element 2a as peripheral temperature drops. COPYRIGHT: (C)2010,JPO&INPIT