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The analog power amplifier (PA) control loop of a fully integrated GSM/GPRS quad-band transceiver, suitable for GSM 850, GSM 900, DCS 1800, PCS 1900, and GPRS class 12 applications is presented. The control loop is based on a fully integrated PA controller (PAC) which meets applicable 3GPP GSM/GPRS specifications. Both the gain and the bandwidth of the PA control loop are programmable as well as the standby voltage delivered to the external PA: these features, together with a high driving capability (8.4 mA at 2.5 V), make this solution capable of interfacing many combinations of PAs, couplers, and detectors. The PAC has been integrated in a BiCMOS SiGe 0.35-μm process and measures 0.33 mm2. The current consumption from a single 2.8-V power supply is 2.8 mA without load and 7.2 mA in the application using Hitachi's PF08109B PA.