Discrete-level envelope tracking for broadband noise-like signals

In this paper we study discrete level supply modulation of an X-band MMIC GaN PA for high-bandwidth signals which statistically resemble band-limited Gaussian noise. 4- and 8-level tracking is compared for various slew rates and the non-linearized NPR is monitored. Two signal bandwidths, 100 and 250 MHz are examined with PAPR of 11 dB and an average PA output power of around 35 dBm. For the 250 MHz signal with 8-level tracking at a slew rate of 1 V/ns a PAE of 40.1 % is measured at 9.8 GHz, compared to 26.2 %, for a fixed 20 V drain voItage.