A Compact Broadband Mixed-Signal Power Amplifier in Bulk CMOS With Hybrid Class-G and Dynamic Load Trajectory Manipulation

This paper presents a mixed-signal power amplifier (PA) with real-time hybrid Class-G and dynamic load trajectory manipulation (DLTM) operation that achieves PA efficiency enhancement into the deep power back-off (PBO) region. Moreover, we dynamically manipulate the PA load impedance trajectory that travels from the optimum output power (Pout) load impedance to the optimum efficiency load impedance during PBO, which creates PA PBO efficiency peaking. The introduced digitally intensive mixed-signal PA architecture enables precise and optimum real-time hybrid PA operation and ensures both PA output amplitude and phase accuracy. DLTM operation also extends the PA RF carrier bandwidth. A prototype PA is fully integrated in a standard 65-nm bulk CMOS process. Its load modulation network is realized by an on-chip compact transformer balun and two on-chip switch-controlled capacitors. The PA achieves +24.6-dBm (+24.4-dBm) peak P out and 45.6% (45.8%) maximum drain efficiency (DE) at 2.4 GHz (2.8 GHz). DLTM operation extends the PA P out and 1-dB bandwidth from 41.7% to 53.8%. By combining the real-time hybrid Class-G and DLTM operation with mixed-signal linearization, the PA delivers +17.6/+17.3-dBm (+17.3/+17-dBm) 10M-Sym/s 64QAM/256QAM at 2.4 GHz (2.8 GHz) with 27.5/26.7% (26.2/24.1%) DE, -29.2/-30.4-dB (-31.3/-31.5 dB) rms error vector magnitude (EVM), and -25.3/-25.1-dBc (-26.4/-26.1-dBc) adjacent channel leakage ratio (ACLR). The total chip area is 1.9 mm 2 .