An E-band QPSK Transmitter Element in 28-nm CMOS with Multistate Power Amplifier for Digitally-Modulated Phased Arrays

This work presents a 2-Gb/s E-band transmitter (Tx) element with a QPSK modulator, injection-lock LO sextupler, all-digital input interface, and a wideband 8-state power amplifier (PA) in 28-nm bulk CMOS. The PA has a saturation power of 15.7 dBm at 78 GHz and power added efficiency (PAE) of 8.9%. The Tx outputs 13.1 dBm when the PA is driven by the modulator, with a system efficiency of 4.7%. The injection-lock LO generation, modulator I/Q correction, and the digitally-modulated PA output magnitude make the Tx element a suitable building block for digitally modulated phased array applications.