A silicon metal-semiconductor-field-effect-transistor (MESFET) power amplifier operating at 900 MHz fabricated on a 45 nm silicon-on-insulator CMOS process with no changes to the process flow is presented. The soft breakdown of the MESFET is 20 times that of the MOSFET and allowed a single transistor amplifier based on Class A bias conditions to operate at up to 32 dBm output power with an 8 V drain bias. The amplifier had a peak power added efficiency of 37.6%, gain of 11.1 dB, OIP3 of 39.3 dBm and 1 dB compression point at an output power of 31.6 dBm. The device required only 0.125 mm 2 of active area. Additionally, the depletion mode operation of the MESFET enables a simple input bias approach using an inductor to ground at the gate of the device.