Bandwidth-Reduced Supply Modulation Of A High-Efficiency X-Band Gan Mmic Pa For Multiple Wideband Signals

This paper introduces bandwidth reduction methods for supply modulation when multiple broadband signals spread over a wide RF bandwidth are simultaneously amplified by a high-efficiency PA. The PA is a GaN on SiC MMIC in the Qorvo 150-nm process with two stages and power combining at the output. With a CW signal at 9.8 GHz, the peak power is 8W with a peak efficiency of 56% and a saturated gain greater than 23 dB. Three 16QAM signals with bandwidths of 1, 2 and 5 MHz, separated by 70 and 130 MHz and centered around 9.8 GHz have a combined envelope bandwidth of > 800 MHz and a PAR around 9.5 dB, which is too large for an efficient envelope modulator. We show that the tracking bandwidth can be significantly reduced when the envelopes of the individual signals are summed at baseband. Measured results show 42.4% PAE and 18.8% worst-case EVM when tracking is used, compared to 29.7% PAE and 14.4% EVM for a fixed supply with no linearization.