Broadband MMIC power amplifier for multiple wireless systems

We report the successful development of a broadband, high-linearity MMIC PA. This single PA is useful for multiple wireless systems including satellite mobile ground terminal, GPS transmitter, WiFi repeater, and WiMAX repeater applications. Using GaAs MESFET technology, we connect two 12 mm FET unit cells both RF and DC in series (HIFET) to achieve a total gate width of 24 mm. This way, the DC bias voltage is doubled from 7 V to 14 V. Because the 12 mm FET´s optimum output impedance is about 6 ohms, a single conventional 24 mm FET´s optimum output impedance will be about 3 ohms. The 2HIFET output optimum impedance is twice that of a 12 mm FET, which is about 12 ohms. This high output impedance leads to broadband capability. This is the key reason that a single MMIC PA can serve multiple wireless system applications. This 2-stage MMIC PA is housed in a commercial ceramic package. It achieves 27 dB small-signal gain, 39 dBm P1 dB, 30% power added efficiency over the 1.5 GHz to 2.5 GHz band. It has good linearity of 51 dBm IP3, which is 12 dB above P1 dB. We believe the combination of bandwidth, output power, efficiency, and linearity is the best reported for MESFET MMIC PA to date.