A 21.08 dBm Q-band power amplifier in 90-nm CMOS process

This paper presents a Q-band four stage power amplifier (PA) fabricated by 90nm CMOS process. In order to improve the output power of the PA, an eight-way distributed active transformer was used for power combining. The simulated insertion loss of the transformer power combiner is less than 1dB at 45 GHz. This paper also shows a way to design transformer baluns for impedance matching. The measurement results of the PA show that the power amplifier achieved 21.08 dBm saturation output power, 20.38 dB small-signal gain and 14.5% power-added-efficiency (PAE) at 45 GHz with 1.2V supply. The entire PA core occupies 0.83mm² die area. And the 3dB bandwidth of the PA is extended from 43 GHz to 47 GHz.