The WEA16S55 is a wide band fractional – N frequency synthesizer with on-chip LO frequency doubler implemented in ST BiCMOS55 process. It uses a 100 MHz to 250MHz Crystal Oscillator/ Input Reference Buffer and generates a 6 GHz to 16 GHz frequency range with the integrated VCOs utilizing a 64 band auto-calibration system. It consists of a an XTAL oscillator, a reference Doubler, a programmable Charge Pump, a low noise phase detector with lock detect indication, 5 bank of VCO, a Prescaler and a 12 bit MASH 1-1-1. The synthesizer is powered by a 1.2 V and 2.5 V supplies.