INVITED PAPER: A 21.5-to-37 GHz Series Doherty CMOS Power Amplifier with Distributed Multi-step Impedance Inverting Network Achieving 28.2%/23.2%/13.2% Peak/OP_1dB/6dB_PBO PAEs

A two-way series Doherty-PA(DPA) with a distributed impedance inverting network (IIN) for millimeter wave applications is presented in this paper. The proposed distributed IIN contributes to achieve wideband linear and PBO efficiency enhancement. Implemented in 65 nm bulk CMOS technology, this work realizes a measured 3 dB bandwidth of 15.5 GHz with 21.2 dB peak small-signal gain at $\mathbf{3 4. 2} \mathbf{G H z}$. Under $1-\mathrm{V}$ power supply, it achieves OP $_{1 \mathrm{~dB}}$ over 13.4 dBm and $P_{\text {sat }}$ over 16 dBm between 21-to-30 GHz. The measured maximum $P_{\text {sat }}$, $\mathbf{O P}_{1 \mathrm{~dB}}$, peak $/ \mathrm{OP}_{1 \mathrm{~dB}} / 6 \mathrm{~dB}_{\text {PBo }} \mathrm{PAE}$ results are $17.5 \mathrm{dBm}, 14.7 \mathrm{dBm}$, and $\mathbf{2 8. 2} \% / 23.2 \% / 13.2 \%$. This work achieves -28.25 dB and -20 dB EVM for a 200 MHz 64-QAM OFDM and a 2 GHz 16-QAM OFDM signals at $27 \mathbf{G H z}$ without DPD and equalization.