Monolithic integrated circuit including gate bias transistor controlling the gate bias applied to an amplifying transistor

摘要

In a semiconductor integrated circuit, an amplifier FET and a gate bias FET, having the same structure as the amplifier FET and a total gate width smaller than that of the amplifier FET, are disposed close to each other. The gate bias FET is a constituent of a gate bias circuit for the amplifier FET, and the current determined by the drain current of the gate bias FET, first and second resistors respectively connected to drain and source of the gate bias FET, and a diode connected in series to the first resistor is applied to the amplifier FET as a gate bias voltage. In this structure, if the DC characteristic of the amplifier FET varies from chip to chip, the DC characteristic of the gate bias FET formed in the vicinity of and simultaneously with the amplifier FET also varies. Therefore, it is possible to make the operating current value of the amplifier FET consistent throughout a plurality of IC chips regardless of differences in the drain current of the amplifier FET, resulting in uniform high frequency characteristics, such as input-output characteristics, of the IC chips.