A Compact 19.7- to 43.8-GHz Power Amplifier With 20.3-dBm Psat and 35.5% PAE in 28-nm Bulk CMOS

This article presents a broadband millimeter-wave (mm-wave) linear power amplifier (PA) to support 5G and beyond wireless communication. An asynchronously tuned coupled resonator (ATCR) circuit model is introduced to effectively design PA's non-ideal transformer-based broadband output matching network (OMN). Two adaptive feedback linearizers (AFLs) and multi-gated transistor (MGTR) techniques are adapted to optimize the linearity. Both amplitude-to-amplitude (AM $-$ AM) and amplitude-to-phase modulation (AM $-$ PM) distortion are improved over one octave with these techniques. A prototype PA is implemented in 28-nm bulk CMOS to verify the proposed ideas. The measured PA realizes 76% $S_{21}$ $-$ 3-dB fraction bandwidth (FBW) from 19.7 to 43.8 GHz, fully supporting five operating bands in 5G new radio (NR) frequency range 2 (FR2), i.e., $n$ 257– $n$ 261. The measured $\vert$ AM $-$ PM $\vert$ is less than 4 $^{\circ}$ over 24 $-$ 43 GHz. The large-signal measurement results show that the PA realizes 18.7 $-$ 20.3-dBm $P_{\mathrm{sat}}$ , 16.8 $-$ 19-dBm OP $_{\mathrm{1dB}}$ , 24.9% $-$ 35.5% PAE $_{\mathrm{max}}$ , and 20.6%–29.7% PAE $_{\mathrm{P1dB}}$ over 22 $-$ 40 GHz. For 5G NR FR2 200-MHz 64-QAM signals 9.7-dB peak-to-average power ratio (PAPR), the PA achieves an average $P_{\mathrm{out}}$ /PAE of 11.0 dBm/8.7% with $-$ 25.2-dB EVM $_{\mathrm{rms}}$ at 24 GHz. The proposed PA achieves a compact size with a core area of 0.088 mm $^{2}$ , making it very suitable for large-scale phased array beamformers.