Monolithic C2L/CMOS frequency synthesizer for CB

Abstract

A MONOLITHIC PHASE-LOCKED LOOP frequency synthesizer for CB will be described. The chip, based on the high speed bulk C2L/CMOS self-aligned silicon-gate technology, is capable of synthesizing frequencies directly for the 40 CB channels in the 26.965-27.405 MHz band. Both high side injection frequencies (37.66-38.10MHz) and low side injection frequencies (16.27-16.71) for a 10.695 MHz intermediate frequency have been demonstrated with this device. Spectral purity, which depends on frequency, for synthesized frequencies is typically 75 dB a t 17 MHz and appears satisfactory for low cost CB transceivers, but is ultimately limited by cross talk on one chip. Studies which also have included an equivalent 2-chip system with the VCO in a separate package, demonstrated that 2-chips can give substantially higher spectral purity and synthesized bandwidth. The selection of a monolithic versus 2-chip system and the most favorable transceiver architecture provide an interesting set of cost versus performance and convenience tradeoffs.