1-W, High-Gain, High-Efficiency, and Compact Sub-GHz Linear Power Amplifier Employing a 1:1 Transformer Balun in 180-nm CMOS

This letter presents a fully integrated two-stage monolithic microwave integrated circuit (MMIC) power amplifier (PA) with a 1:1 transformer balun in Taiwan Semiconductor Manufacturing Company (TSMC) 180-nm CMOS process. To optimize the performance of PA, an on-chip 1:1 turn spiral transformer balun (STB) was used with a high supply power through the cascode topology. The proposed PA achieved a 40-43-dB gain and a saturation power (P
_sat
) of 29.9-30.3 dBm with a 40%-45% of power-added efficiency (PAE) in the frequency range of 820-1000 MHz. Using the antiphase biasing technique, the PA achieves a linear output power of 25 dBm with 29.5% PAE in 20-MHz spacing two-tone measurement, which satisfies IMD3 <; -25 dBc. The measured 1-dB compression point was 28.1 dBm. Furthermore, the proposed PA occupied a core area of 3.3 × 0.86 mm
²
.