Am broadcast receiving circuit

Abstract

A JFET 4 to be an antenna buffer for an AM broadcasting signal is constituted in a source follower form of a 100% negative feedback type, and a tuning circuit including a variable capacitive circuit 7 and a transformer 6 is provided in a subsequent stage to the JFET 4 and an amplifying circuit including MOSFETs 10 and 11 is provided in a further subsequent stage thereto. Consequently, it is possible to reduce a signal distortion rate in the JFET 4 and to eliminate a drawback that every frequency component enters the amplifying circuit to saturate the amplifying circuit, resulting in an occurrence of a distortion in an output signal. By switching a plurality of capacitors CT1, CT2, . . . CTn to cause a capacitance value to be variable without using a varactor diode, it is possible to integrate the capacitors CT1, CT2, . . . CTn in an IC 20.

Dependencies are inferred from the claim text.