Analysis and Design of Milimeter-Wave Neutralized Power Amplifiers in 65-nm CMOS

This paper presents two single-stage common-source differential power amplifiers (PAs) at 28 GHz. One PA utilizes the metal-oxide-metal (MOM) capacitor neutralization topology and the other adopts the NMOS transistor capacitor neutralization. The input and output matching networks of the two PAs are both implemented by transformers, which are carefully optimized to enhance high load capacity and efficiency. Fabricated in 65-nm CMOS technology, the PA with MOM capacitor neutralization shows a measured small-signal gain of 7.05 dB and a peak power added efficiency (PAE) of 27.52%. The PA with NMOS neutralization achieves a small-signal gain of 6.17 dB with a peak PAE of 25.54%. By comparison under the same DC consumption, the latter presents higher stability and broader bandwidth at the cost of gain and efficiency.