Description
The Si4133 is a monolithic integrated circuit that performs both IF and dual band RF synthesis for wireless communications applications. The Si4133 includes three VCOs, loop filters, reference and VCO dividers, and phase detectors. Divider and power down settings are programmable with a three wire serial interface.

FEATURES
■ Dual-band RF synthesizers
    •RF1: 900 MHz to 1.8 GHz
    •RF2: 750 MHz to 1.5 GHz
■ IF synthesizer
    •IF: 62.5 to 1000 MHz
■ Integrated VCOs, loop filters, varactors, and resonators
■ Minimal (2) number of external components required
■ Low phase noise
■ Programmable powerdown modes
■ 1 µA standby current
■ 18 mA typical supply current
■ 2.7 to 3.6 V operation
■ Packages: 24-pin TSSOP, 28-lead QFN
    •Lead-free and RoHS compliant

Applications
■ Dual-band communications
■ Digital cellular telephones GSM 850, E-GSM 900, DCS 1800, PCS 1900
■ Digital cordless phones
■ Analog cordless phones
■ Wireless local loop