Published:2011/5/10 1:14:00 Author:Fiona | Keyword: radio monolithic integrated | From:SeekIC
CD2003 is an AM / FM radio monolithic integrated circuit，it has been widely used in the desheng series radio.1. Features CD2003 integrated circuit contains AM HF amplifier, local oscillator, mixer, IF amplifier and detector circuit ;FM HF amplifier, local oscillator, mixer, IF amplifier and discriminator circuit : and the AGC circuit, AM / FM band selection circuit etc, the block diagram of the in-circuit is shown in Figure 1. Figure 1 CD2003 integrated circuit within the circuit block diagram and typical application circuit2.pin functions and data CD2003 integrated circuit uses 16-pin dual in-line Package,the pin functions and typical operating parameters(Vcc = 3V time, the pin voltage in AM and FM both cases,) are listed in table 1,the pin function and the test data on the desheng multi-band radio are listed in the table 2. Table 1 CD2003 integrated circuit pin functions and typical operating parameters Table 2 CD2003 integrated circuit pin functions and test data on the desheng multi-band radio 3.Typical application circuit Illustration 1 is a typical application circuit of AM / FM band radio formed by the CD2003 integrated circuit.the work process1) AM band.The signals received from Antenna input from the CD2003 (16) pin ,mixing with the LO signal in the mixing circuit.The signal obtained output from (4) pin , obtaining the 465kHz IF signal selected by frequency to input from the (7) pin.After being converted by the IF amplification, detection, electronic switch, the signals output from (11) pin to reach the post-stage circuit. (2)FM band.The signals received from Antenna input from the (1) pin after being band-pass filtered by the BPF,added to the mixing circuit after HF amplifier.Mixing with the LO signal in the mixing circuit,the signal obtained output from (3) pin , obtaining the 10.7MHz IF signal selected by frequency to input from the (8) pin.After being converted by the AM / FM electronic switch, the signals output from (11) pin to reach the post-stage circuit.Tip:According to the above-mentioned signal flow ,it's convenient to repair AM or FM radio with sound or radio trouble.Becauce CD2003 will not easily damaged,we should pay attention to the periphery of its three-terminal filters to be checked.
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