A Highly Linear and Efficient $V$ -Band CMOS Power Amplifier Using Hybrid NMOS/PMOS for Double Nonlinearity Cancellation With Four-Way Distributed-Active-Transformer

This article presents a
$V$
-band (i.e., 47-75 GHz) differential four-way distributed-active-transformer (DAT) power amplifier (PA), which uses hybrid NMOS/PMOS for double nonlinearity cancellation to improve the linearity with minimal impact on the overall PA efficiency. Implemented in the 45-nm CMOS silicon-on-insulator (SOI) process, the proposed PA consists of three stages, pre-driver, driver, and PA stages, to deliver the desired gain at the
$V$
-band. The PA stage includes both NMOS and PMOS transistors, while the driver stage adopts PMOS and the pre-driver stage uses NMOS transistors. This mixed NMOS/PMOS scheme provides a high-order nonlinearity cancellation, substantially improving the PA linearity, and optimizes its performance. An ultra-compact differential four-way series–parallel DAT-based power combiner is used to provide the optimum load (R
$_{\text{opt}}$
) to the mixed NMOS/PMOS PA. This proposed PA output matching network/power combiner only occupies one transformer footprint, resulting in a reduced chip area and design complexity. The PA achieves peak power-added-efficiency (PAE) of 35.4%, saturation power (P
$_{\text{sat}}$
) of 16.3 dBm, and AM–PM distortion
$<$
2
$^{\circ}$
(at output 1-dB compression point–13.5 dBm) in 50.4-58 GHz. The AM–PM distortion drops
$<$
0.5
$^{\circ}$
at 55 GHz. The PA exhibits an average PAE (PAE
$_{\text{avg}}$
) of 15.6% and rms error vector magnitude (EVM)
$<$

$-$
25 dB when transmitting a 64-QAM modulated signal with 9.5 dBm average output power (P
$_{\text{avg}}$
) at 0.5 GSym/s. The EVM remains better than
$-$
24 dB at 3 GSym/s with P
$_{\text{avg}}$
of 8.1 dBm (PAE
$_{\text{avg}}$

$=$
9.1%). In addition, this PA is measured by 5G NR CP-OFDM 64-QAM modulation with multiple CCs. When using 1-CC FR2 400-MHz modulation, it achieves PAE
$_{\text{avg}}$
of 14.5%, P
$_{\text{avg}}$
of 10 dBm, EVM of
$-$
23.5 dB, and adjacent channel power ratio (ACPR) of
$-$
25.8 dBc. For 4-CC FR2 200-MHz modulation, the PA exhibits PAE
$_{\text{avg}}$
of 8.1%, P
$_{\text{avg}}$
of 8 dBm, EVM of
$-$
24.6 dB, and adjacent power channel ration (ACPR) of
$-$
24.6 dBc.