A Quadrature Hybrid Coupler Based T/R Front-End

This paper presents a quadrature hybrid coupler (QHC) based transmit-receive (T/R) front-end module (FEM). The QHC offers impedance transformation over a large band-width and power combining during the transmit mode. A 38 GHz T/R FEM is designed in a 65-nm CMOS process to validate the concept. The QHC is realized using lumped inductors and capacitors. The power amplifier (PA) has a 3-dB bandwidth of 7 GHz, from 34 GHz to 41 GHz. Post layout simulations show a saturated output power (Psat) of 17.3 dBm with 13.5 % power added efficiency (PAE) at 38 GHz. The lower noise amplifier (LNA) has 16.5 dB voltage gain and 5.6 dB noise figure (NF) at 38 GHz while consuming 8.72 mW power.