A time-domain duplexing radio frequency (RF) front-end with integrated antenna switch, power amplifier (PA), and low noise amplifier (LNA) was developed aiming for fifth-generation communication (5G) applications covering 24–28 GHz frequency range. Antenna switch utilizes pre-existing LNA input matching network together embedded with grounded shunt transistor switch to provide sufficient isolation of receive side from PA. Respectively, high impedance of off-state PA is assumed to achieve acceptable receive performance. Resulting output power is 13.6 dBm with 15 dB of peak small-signal gain at 28 GHz. Maximum average channel power was 4.8 dBm with 100 MHz 64-QAM OFDM signal within 5G adjacent channel power ratio and error vector magnitude specifications. Receive (RX) front-end achieves 5 dB noise figure at 24 GHz and 7 dB of peak gain. Performances of amplifiers degraded only by 2 dB from switch integration. The front-end dissipates 183 and 4.6 mW of power in transmit and receive mode, respectively. The simplistic design method minimizes cost both in circuit area (only 0.19 mm2) and design time making this front-end an attractive alternative in massive phased array applications using 22 nm complementary metal oxide semiconductor (CMOS) fully depleted silicon on insulator process.

The design of a subharmonic downconverter for 94-GHz imaging arrays in SiGe:C technology is presented. A three-stage differential low-noise amplifier (LNA) with lumped matching networks is used together with a subharmonic mixer driven by a single-pole local-oscillator poly-phase network to form the front-end. The LNA yields 15 dB gain at 94 GHz, while the mixer provides 5 dB conversion gain over a 10 GHz IF bandwidth. The integrated downconverter provides 20 dB conversion gain at 94 GHz with an input 1-dB compression point of −31 dBm and has a current consumption of 45 mA at a 3.3 V supply voltage. The total required die area of the complete downconverter (excluding pad frame) is 0.1 mm, thus making it particularly suitable as a front-end in multi-channel receiver systems.