An X-/Ku-Band CMOS Broadband Power Amplifier with Transformer-Coupled Resonator

This paper presents a broadband X-/Ku-band power amplifier (PA) with transformer-coupled resonator (TCR) for FMCW radar application. Interaction between the active and passive circuits is considered in PA design. The TCR is exploited to construct the output current of PA active circuit. With the cooperation between the TCR and the active part of PA, a uniform output power in a wide frequency range can be achieved. Fabricated in a 110-nm CMOS technology, the proposed PA exhibits 19.5-dB power gain (S
21
) with 3-dB bandwidth (BW) from 9.48 to 15.5 GHz (48.2% fractional BW). The measured large-signal performance versus frequency shows a wide 1-dB BW for P
sat
over 8.5-14.5 GHz (52.2% fractional BW) with 15.7-dBm peak value and 27% peak PAE
max
at 11.5 GHz, demonstrating the broadband design for PA.