A Ku-band power amplifier MMIC has been developed using 0.25-mum GaAs pHEMT technology. To achieve small chip size and simple drain-bias connection, a bus-bar power combiner is used. Also, balanced-power amplifier topology is used to obtain good input/ output return losses. The small-signal gain is about 15 dB and the gain variation is less than 1 dB from 12 to 17 GHz. Good input/output return losses are achieved at less than -15 dB due to the balanced topology. P-IdB of 32.6 dBm and PAE of 23.5% are achieved at 14 GHz. The effective chip area is 4.2 X 3.2 mm. Because the power amplifier is implemented using the balanced topology with the bus-bar power combiner, compact size, high output power, and good input/output return losses can be achieved simultaneously. (C) 2004 Wiley Periodicals, Inc.