2.6 A SiGe BiCMOS E-band power amplifier with 22% PAE at 18dBm OP1dB and 8.5% at 6dB back-off leveraging current clamping in a common-base stage

Several spectrum portions at mm-waves are considered for Gb/s data-rates in 5G cellular wireless backhaul and access networks, further motivating innovation in circuits and systems for efficient transceivers [1,2]. Small or pico-cell networks are required for spatial diversity and propagation-loss compensation, suggesting silicon solutions also for backhauling where the E-band is a candidate. Techniques for spectral and power efficiency are being investigated, key for capacity improvements over LTE and deployment of the large number of required cells. A transmitter power amplifier (PA), delivering near 20dBm, is a key block for power saving. With the high peak-to-average ratio of QAM modulations, PAs are operated at 5-to-8dB back-off [2], where the efficiency of reported silicon E-band PAs is in the order of a few percent only [3-5].