A 26.5–29.5 GHz Doherty PA-LNA Implementation With Synthesized Transformer-Based Matching Network

Millimeter-wave (mm-Wave) transceivers with high power, enhanced peak/back-off efficiency, and low noise are highly desired in 5G New Radio (NR) systems. This article presents a 26.5–29.5-GHz Doherty power amplifier (PA)-low noise amplifier (LNA) with a compact transformer-based matching network (MN). The boundary conditions of a three-port Doherty PA-LNA combiner network are thoroughly analyzed. Building on this analysis, a novel transformer-based MN topology is proposed, enabling simultaneous realization of Doherty operations, noise matching, and high isolation within a time-division duplex (TDD) transmit/receive (T/R) front-end. To validate this concept, a Doherty PA-LNA prototype is designed and fabricated in 65-nm bulk CMOS, occupying a core area of $1.3\times 0.65$ mm2. In TX mode, it achieves a maximum output 1-dB gain compression point (OP1dB) of 17.5-dBm with a power-added efficiency (PAE) of 14.6% at 6-dB power back-off (PBO). The drain efficiency (DE) exhibits a superior 1.66 times efficiency enhancement over the normalized class-B DE at 6-dB PBO. In RX mode, it achieves a minimum noise figure (NF) of 4.8 dB at 28.6 GHz with an in-band NF ranging from 4.8 to 5.4 dB. The chip consumes 255 mW at OP1dB in TX mode and 33 mW in RX mode.