A 60MHz Bandwidth High Efficiency X-Band Envelope Tracking Power Amplifier

This paper presents a high efficiency X-band envelope-tracking power amplifier (PA) that achieves a 60MHz modulation bandwidth. The system consists of a wideband envelope modulator and a single-chip gallium- nitride (GaN) MMIC X-band PA. The envelope modulator achieves >70% efficiency while delivering >7W into an 8Ω resistive load for a 60MHz LTE-A modulated signal with a 6.6dB PAPR. The envelope tracking system attains a PAE of 35.3% (including the power dissipation of the envelope modulator) with 1.1W of average output power at 9.23GHz using a 20MHz LTE signal. The X-band PA itself was measured to achieve a drain efficiency of 81.6% with a gain of 7.6dB under these conditions.