The LMX2353 is a monolithic integrated fractional N frequency synthesizer, designed to be used in a local oscillator subsystem for a radio transceiver. It is fabricated using National's 0.5 ABiC V silicon BiCMOS process. The LMX2353 contains dual modulus prescalers along with modulo 15 or 16 fractional compensation circuitry in the N divider. A 16/17 or 32/33 prescale ratio can be selected for the LMX2353. Using a fractional N phase locked loop technique, the LMX2353 can generate very stable low noise control signals for UHF and VHF voltage controlled oscillators (VCO's). The LMX2353 has a highly flexible 16 level programmable charge pump supplies output current magnitudes from 100 A to 1.6 mA. Serial data is transferred into the LMX2353 via a three wire interface (Data, LE, Clock). Supply voltage can range from 2.7V to 5.5V. The LMX2353 features very low current consumption; typically 4.5 mA at 3.0V. The LMX2353 is available in a 16-pin TSSOP or a 16-pad CSP surface mount plastic package.