Gate control of a two-stage GaN MMIC amplifier for amplitude and phase linearization

In this paper we study static and dynamic gate biasing of a two-stage X-band MMIC GaN PA. The PA is first characterized under different bias conditions using large-signal static measurements, and the determined conditions are then applied to dynamic measurements with a 20 MHz noise power ratio (NPR) test signal. Biasing the gates of the two stages independently allows simultaneous reduction of amplitude and phase distortion. AM/AM, AM/PM and PAE measurements are obtained for three different static scenarios. Consistent results from static and dynamic tests are obtained showing NPR values exceeding 31 dB. Adding predistortion alters the efficiency of the investigated static biases by more than 4 % points.