Radio Frequency Domain Calibration for Phased-Array Transmitter and Receiver Front-Ends With Improved Phase and Gain Accuracy

Abstract

K-/Ka-band phased-array transmitter (TX) and receiver (RX) front-ends for satellite communication (SATCOM) with phase and gain control calibration are proposed. The calibration of a quadrature all-pass filter (QAF) for precise phase control in the phase shifter (PS) is based on a novel compensation transistor serving as a tunable resistor. The calibration of a variable-gain amplifier (VGA) in the attenuator (ATT) for precise amplitude control with minimized additional phase shift is based on novel compensation capacitances. The RX noise figure (NF) and TX linearity have been improved based on fine-tuning of the circuit parameters. As implemented in a 40-nm CMOS process, the eight-channel transceiver (TRX) front-ends exhibit a 360° phase-shifting range with 7-bit resolution (2.8125°) and a 31.5-dB attenuation range in 0.5-dB steps. For the RX chain and the TX chain, the measured root mean square (rms) phase errors with QAF calibration are 0.05°–0.06° and 0.04°–0.08°, respectively, while the corresponding rms gain errors are 0.05–0.08 dB and 0.05–0.06 dB, and the rms additional phase shifts are 0.09°–0.17° and 0.1°–0.17°. The RX exhibits an EVM of −35.8 dB at 400 MHz 256 QAM with −33-dBm input power. With an EVM of −30.1 dB at 400 MHz 256 QAM, the corresponding TX output power is 7.7 dBm. The rms phase error, rms gain error, rms additional phase shift, and EVM are better than the previously reported results, with other performances of the TRX comparable to the prior state of the art.