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A digitally-controlled power amplifier (DPA) in 0.13-mum 1.2-V SOI-CMOS is demonstrated, to be used as a building block in a multi-standard radio transmitter. The circuit performs direct amplitude modulation of an input RF carrier, by digitally controlling a large array of RF gain cells. It exhibits a 24.5-dBm peak output power at 1.9 GHz, and an effective resolution better than 7 bits. A novel two-stage topology for the gain cell is described, which allows the DPA to seamlessly operate from 800 MHz through 2 GHz, with a full-power efficiency larger than 40% and a small-signal gain of 14.5 dB. A new strategy is also proposed to provide a wide-range transmit power control.