A K_a-Band Transformer-Based Switchless Bidirectional PA-LNA in 90-nm CMOS Process

This paper presents a switchless bidirectional power amplifier-low noise amplifier (PA-LNA) in 90-nm CMOS process for millimeter-wave (mm-wave) phased-array front-end chip. This PA-LNA uses current-type transformer (TF) as a bidirectional matching network for PA and LNA inputs/outputs without using lossy T/R switches. As a side benefit, avoiding the use of the T/R switches not only saves the chip area, but also prevents performance degradation in PA and LNA modes. The proposed PA-LNA achieves peak small-signal gain of 18.3 dB and 17.6 dB in PA and LNA mode, respectively. In the PA mode, it achieves the measured peak saturated output power (Psat) of 15.1 dBm with 29 % peak power-added efficiency (PAE <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">MAX</inf> ) and 13.3 dBm peak 1-dB output power (OP <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1dB</inf> ) at 33 GHz, while LNA mode achieves minimum noise figure (NF) of 4.7 dB at 36 GHz. The reverse isolation in both modes is better than 43 dB. The core size without pads is 0.21 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .