The LMX2354 is part of a family of monolithic integrated fractional N/Integer N frequency synthesizers 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 LMX2354 contains quadruple modulus prescalers along with modulo 15 or 16 fractional compensation circuitry in the RF divider. The LMX2354 provides a continuous divide ratio of 80 to 32767 in 16/17/20/21 (1.2 GHz2.5 GHz) fractional mode and 40 to 16383 in 8/9/12/13 (550 MHz1.2 GHz) fractional mode. The IF circuitry for the LMX2354 contains an 8/9 prescaler, and is fully programmable. Using a fractional N phase locked loop technique, the LMX2354 can generate very stable low noise control signals for UHF and VHF voltage controlled oscillators (VCOs). For the RF PLL, a highly flexible 16 level programmable charge pump supplies output current magnitudes from 100 A to 1.6 mA. Two uncommitted CMOS outputs can be used to provide external control signals, or configured to FastLock mode. Serial data is transferred into the LMX2354 via a three wire interface (Data, LE, Clock). Supply voltage can range from 2.7V to 5.5V. The LMX2354 family features very low current consumption; typically LMX2354 (2.5 GHz) -- 7.0 mA. The LMX2354 are available in a 24-pin TSSOP surface mount plastic package and 24-pin CSP.