A single supply 2W MMIC power amplifier, operating between 3.3GHz and 3.8GHz by implementing AlGaAs/InGaAs/GaAs PHEMT for the applications of WiMax, is demonstrated. Using the gate zero-bias configuration, i.e., VGS=0 and IDss, one can use only one single bias instead of dual bias in the depletion mode PHEMTs. This two-stage amplifier is designed by using a zero gate bias configuration i.e., VGS=0 and at saturated drain current IDSs, for class A power amplifier operation. The two-stage MMIC amplifier possesses the characteristics of 25.9dB small-signal gain and 34.0dBm 1-dB gain compression power. Moreover, with a single carrier output power level of 21dBm, very high linearity with a 47dBm third-order intercept point operating at 3.5GHz is also achieved.