A 9.5-to-40 GHz Ultra-Broadband Linear Power Amplifier with Compensated Coupled-Line Transformer in 65-nm Bulk CMOS

This paper presents a 9.5–40 GHz high-power, ultra-broadband linear power amplifier (PA) in 65-nm bulk CMOS technology for 5G FR2 and future 6G applications. To achieve such broadband high-power performance, a compensate-ed coupled-line transformer (CCLT) is proposed. Based on even- and odd-mode analysis, the proposed CCLT absorbs the output capacitances of the device into the network while offering an arbitrary impedance transformation ratio. The prototype PA achieves a peak small-signal gain of 17.3 dB with a 3-dB bandwidth of 9.5–40 GHz. In continuous-wave measurements, the PA demonstrates a saturated output power of 21.8–23.8 dBm across 9–40 GHz, which corresponds to a 2-dB fractional bandwidth of 126.5%. Additionally, the PA achieves a maximum power-added efficiency (PAE) of 23.9%–40.4% across the band. Furthermore, under a 400-MHz 64-QAM 5G NR FR2 signal (9.7-dB PAPR), it delivers an average output power of 12.9–16.4 dBm and an average PAE of 5.2%–11.7% across 10–40 GHz.