The U2894B is a monolithic integrated circuit. It is realized using TEMIC's advanced silicon bipolar UHF5S technology. The device integrates a mixer, an I/Q modulator, a phase-frequency detector (PFD) with two synchronous programmable dividers, and a charge pump. The U2894B is designed for cellular phones such as GSM900, DCS1800, and PCS1900, applying a transmitter architecture at which the VCO operates at the TX output frequency. No duplexer is needed since the outof-band noise is very low. The U2894B exhibits low