IMI145151

IMI145151 PRODUCT DESCRIPTION FREQUENCY SYNTHESIZER CMOS LSI PARALLEL PROGRAMMED PLL FREQUENCY SYNTHESIZER PRODUCT FEATURES The IMI145151 is a member of a family of phaselock loop synthesizer ICs from International Microcircuits. The IMI145151 is an improved version of the Motorola MC145151 and will provide a synthesizer with noticeably improved performance. The IMI145151 is programmed with parallel input data lines. Since it does not require a microcontroller as serial and bus programmed units do, the IMI145151 is an excellent choice for synthesizers requiring independence from digital controllers. Such applications include fixed local oscillator signals, whose tuning never changes, and signal sources, which have few operating frequencies. Blocks in the IMI145151 include a programmable feedback divider, a reference divider, phase detector, and charge pump. The reference divider is programmed by three select lines to one of eight ROM encoded values. Both counter inputs are biased for maximum sensitivity to sinewave input signals. The reference divider input is also configured to operate as a crystal oscillator if desired. The IMI145151 has a Type IV phase frequency detector which has eliminated by the design the inherent dead zone which causes crossover distortion at the critical center lock point. the IMI circuitry enables consistent low noise loop designs using the simple single ended charge pump output. Differential charge pump outputs are also provided for those who req...