FM radio circuit composed of field effect tubes

Shown is an FM radio circuit composed of a double -gate MOS field effect transistor . The high-frequency amplifier is composed of a two-pole MOS field effect transistor amplifier (VTI, VT2). VT3 is a mixer. The local oscillator is composed of VT4, and the high-frequency signal is added to the first gate of VT3. The high-frequency signal is frequency-selected by the LC tuning circuit and sent to the gate of VT1. After amplification, it is coupled to the second-stage high-frequency amplification There is also an LC frequency-selective resonance at the input end of the second-stage high-frequency amplification. circuit. In this way, after two stages of high-frequency amplification and frequency selection circuits, it is sent to the first gate of the mixing stage VT3. VT4 generates a local oscillation signal, which is amplified by VT5 and then added to the second gate of the mixing stage field effect transistor VT3 . The intermediate frequency signal (10.7 MHz) formed after mixing is frequency selected and output by the intermediate frequency transformer (L4).