MP3 FM radio circuit

Shown is the FM radio circuit of MP3 . The chip of this circuit is JFR-104. In the radio state, the socket of the earphone serves as the antenna of the FM radio circuit. The FM radio program signal received by the antenna is sent to the ① pin of JFR-104. The signal is a radio frequency carrier wave emitted by a broadcast station . High-frequency amplification, mixing, intermediate frequency amplification, frequency identification and other processes are performed in the JFR-104 chip to demodulate the audio signal, which is then sent to the CPU and decoder circuit ACU7505 for processing through the ④ and @ pins. The JFR-104 The @ pin and @ pin receive the control data signal and clock signal from the main chip CPU . These two signals, together with the radio control signal from the CPU, are added to the gate of VT1, and are supplied to the power supply of JFR-104 through VTI control, thus To achieve the purpose of controlling the radio.