文档网址：宝贝描述：DESCRIPTIONThe NE568A is a monolithic phase-locked loop (PLL) whichoperates from 1Hz to frequencies in excess of 150MHz and featuresan extended supply voltage range and a lower temperaturecoefficient of the VCO center frequency in comparison with itspredecessor, the NE 568. The NE568A is function andpin-compatible with the NE568, requiring only minor changes inperipheral circuitry (see Figure 3). Temperature compensationnetwork is different, no resistor on Pin 12, needs to be grounded andPin 13 has a
3.9kW resistor to ground. Timing cap, C2, is differentand for 70MHz operation with temperature compensation networkshould be 16pF, not 34pF as was used in the NE568. The NE568Ahas the following improvements: ESD protected; extended VCCrange from
4.5V to
5.5V; operating temperature range -55 to 125 °C(see Signetics Military 568A data sheet); less layout sensitivity; andlower TC of VCO (center frequency). The integrated circuit consistsof a limiting amplifier, a current-controlled oscillator (ICO), a phasedetector, a level shift circuit, V/I and I/V converters, an output buffer,and bias circuitry with temperature and frequency compensatingcharacteristics. The design of the NE568A is particularly well-suitedfor demodulation of FM signals with extremely large deviation insystems which require a highly linear output. In satellite receiverapplications with a 70MHz IF, the NE568A will demodulate ±20%deviations with less than
1.0% typical non-linearity. In addition tohigh linearity, the circuit has a loop filter which can be configuredwith series or shunt elements to optimize loop dynamicperformance. The NE568A is available in 20-pin dual in-line and20-pin SO (surface mounted) plastic packages淘宝：s:13670099459