Abstract
This paper presents a 28-GHz compact high-power TRX phased-array beamformer implemented in 40-nm CMOS for 5G applications. A high-power PA-LNA integrates a parallel combining transformer (PCT) embedded T/R switch, achieving high output power and low noise figure. Meanwhile, a frequency-selective suppression technique (FSST) is employed in the interstage matching network to introduce the transmission zero, enhancing out-of-band signal suppression. Additionally, a bidirectional phase shifter is proposed for precise phase control, which enables a compact beamformer implementation. The beamformer demonstrates the measured peak gains of 22/24 dB in TX/RX mode. The measured peak P-SAT/P-1dB is up to 21.3/19.8 dBm, the PAE(max)/PAE(P1dB) is 18.3%/15.9%. The measured minimum NF is 5.2 dB. With a 64-QAM 400 MSym/s single-carrier signal, it achieves a P-OUT,P- AVG of 15.9 dBm and a PAEAVG of 8.3% at EVMrms of -24.9 dB. The four-element beamformer occupies only 3.6mm(2).