Design of CMOS-Based Unit Channel of Beamforming Transceivers for FACS Applications

In this study, we designed the unit channel of beamforming transceivers for flexible access common spectrum (FACS) applications. The designed unit channel consisted of power amplifier, low noise amplifier, gain amplifier, attenuator, phase shifter, and switches. In particular, in this study, in order to miniaturize the entire system, the 180 degrees phase shift function of the phase shifter was implemented in the power amplifier and the low noise amplifier. At this time, the area of the phase shifter was reduced without increasing the area of the power amplifier and the low noise amplifier with the 180 degrees phase shift function. In addition, the stagger tuning technique was applied to the amplifiers constituting the unit channel to secure bandwidth. The designed unit channel was fabricated using 65-nm RFCMOS process. The operating frequency range was 22.0 GHz to 23.6 GHz. At 23.6 GHz, when the bandwidth of the 64-QAM 5G NR modulated signal was 100 MHz, 200 MHz, and 400 MHz, the output power satisfying 5.62% of EVM was measured as 9.79 dBm, 7.82 dBm, and 4.47 dBm, respectively. The noise figure (NF) in Rx mode was measured to be less than 4.88 dB.