Future mm-Wave transmitter front-ends will need to operate in an electromagnetically complex environment that are resistant to near-field antenna perturbations (VSWR events) while operating across multiple mmWave frequency bands (28/37/39/42 GHz) and with high efficiency and linearity with spectrally efficient modulation. This is particularly difficult since these parameters (bandwidth, linearity, efficiency, and VSWR tolerance) trade off strongly with each other in a power amplifier (PA). In this paper, we present a PA architecture that exploits mutual load pulling through a multi-port network in a nonlinear fashion to achieve VSWR tolerance while demonstrating Doherty-like operation across 26-42 GHz. The PA designed in 65-nm bulk CMOS generates P-sat \gt 19 dBm with PAE -peak \gt 20% across all bands and achieves up to 3.35x and 4.84x enhancement in PAE at back-off power levels of 6 and 9.6 dB over class-A operation. In addition, the PA demonstrates strong tolerance to VSWR events with only 2 dB degradation over a VSWR 4:1 load circle and supports 64QAM OFDM modulation with 8 Gbps across 28-40GHz.