Radio Tuning PLL Frequency Synthesizer SAA1057

Tuesday, October 3rd, 2017 - Radio Frequency

General Description Of Radio Tuning PLL Frequency Synthesizer SAA1057

The SAA1057 is a single chip frequency synthesizer IC in I2L technology, which performs all the tuning functions of a PLL radio tuning system. The IC is applicable to all types of radio receivers, e.g. car radios, hi-fi radios and portable radios. The SAA1057 performs the entire PLL synthesizer function (from frequency inputs to tuning voltage output) for all types of radios with the AM and FM frequency ranges. A reference frequency oscillator followed by a reference divider. The frequency is generated by a 4 MHz quartz crystal. The reference frequency can be chosen either 32 kHz or 40 kHz for the digital phase detector (that means 1 kHz and 1,25 kHz for the sample and hold phase detector), which results in tuning steps of 1 kHz and 1,25 kHz for AM, and 10 kHz and 12,5 kHz for FM. A programmable current amplifier (charge pump), which controls the output current of both the digital and the sample/hold phase detector in a range of 40 dB. It also allows the loop gain of the tuning system to be adjusted by the microcomputer.

Standart Aplication Of Radio Tuning PLL Frequency Synthesizer SAA1057

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Features Of Radio Tuning PLL Frequency Synthesizer SAA1057

  • On-chip prescaler with up to 120 MHz input frequency.
  • On-chip AM and FM input amplifiers with high sensitivity (30 mV and 10 mV respectively).
  • Low current drain (typically 16 mA for AM and 20 mA for FM) over a wide supply voltage range (3,6 V to 12 V).
  • On-chip amplifier for loop filter for both AM and FM (up to 30 V tuning voltage).
  • On-chip programmable current amplifier (charge pump) to adjust the loop gain.
  • Only one reference frequency for both AM and FM.
  • High signal purity due to a sample and hold phase detector for the in-lock condition.
  • High tuning speed due to a powerful digital memory phase detector during the out-lock condition.
  • Tuning steps for AM are: 1 kHz or 1,25 kHz for a VCO frequency range of 512 kHz to 32 MHz.
  • Tuning steps for FM are: 10 kHz or 12,5 kHz for a VCO frequency range of 70 MHz to 120 MHz.
  • Serial 3-line bus interface to a microcomputer.
  • Test/features.

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