Broadband MMIC power amplifier for multiple wireless systems

Abstract

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 12mm FET unit cells both RF and DC in series (HIFET) to achieve a total gate width of 24mm. This way, the DC bias voltage is doubled from 7V to 14V. Because the 12mm FET's optimum output impedance is about 6 ohms, a single conventional 24mm FET's optimum output impedance will be about 3 ohms. The 2HIFET output optimum impedance is twice that of a 12mm 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 27dB small-signal gain, 39dBm P1dB, 30% power added efficiency over the 1.5GHz to 2.5GHz band. It has good linearity of 51dBm IP3, which is 12dB above P1dB. We believe the combination of bandwidth, output power, efficiency, and linearity is the best reported for MESFET MMIC PA to date.