A 28GHz Compact Phased-Array Beamformer with 21.3dBm PSAT and 5.2dB Noise Figure in 40NM CMOS

This paper presents a 28-GHz compact high-power TRX phased-array beamformer implemented in 40-nm CMOS for 5 G 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 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{P}_{\text{SAT}} / \mathrm{P}_{1\text{dB}}$</tex> is up to 21.3/19.8 dBm, the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{PAE}_{max}/\text{PAE}_{\text {P1dB}}$</tex> is 18.3%/15.9%. The measured minimum NF is 5.2 dB. With a 64-QAM 400 MSym/s singlecarrier signal, it achieves a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$P_{OUT,AVG}$</tex> of 15.9 dBm and a PAEAVG of 8.3% at <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{EVM}_{\text{rms}}$</tex> of −24.9 dB}. The four-element beamformer occupies only <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$3.6 ~\text{mm}^{2}$</tex>.