A K / Ka -Band Transmit/Receive Front-End With Triple-Coupled Transformer Technique in 65-nm Bulk CMOS

This article presents a K/Ka-band transmit/receive (T/R) front-end for jointed sensing and communication (JSAC) applications. A reconfigurable matching network for both signal reception and transmission is realized using the proposed triple-coupled transformer (TCT) technique, achieving low power loss and a compact footprint. The T/R switch at the center tap of the low-noise amplifier (LNA) coil enhances the T/R isolation by cutting off the coupled leakage power from the power amplifier (PA) coil. The chip was fabricated in 65-nm bulk CMOS and occupies a 1.18-mm2core area. In the RX mode, it achieves a power gain of 24.7–27.6 dB and an NF less than 5 dB at 17.7–29.5 GHz. In the TX mode, it achieves a maximum saturated output power ($P_{\text {sat}}$) of 20.5 dBm with a power added efficiency (PAE) of 21.8% and an output-referred 1-dB gain compression point ($\text {OP}_{\text {1dB}}$) of 20.2 dBm with a PAE of 20.6% at 24 GHz. The measured$\text {OP}_{\text {1dB}}$is larger than 16.7 dBm over the 20–31-GHz frequency range. The chip demonstrates low noise figure (NF) and high output power among K/Ka-band silicon-based T/R front-ends.