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The challenges associated with efficiently and effectively linearizing a nonlinear power amplifier (PA) over wide signal bandwidths are increasingly important to the design of 5G front-ends. Conventional digital linearization techniques are limited by absolute bandwidth, while the RF-domain nonlinear PA typically exhibits consistent fractional bandwidth even as the carrier frequency is increased. Therefore, RF-domain design techniques, like those focusing on bias-line impedance selection, are critical for overall distortion reduction. To evaluate bias-line effects, a demonstrator PA is here investigated over a range of Class-AB biases and over a range of drain inductance values. The characterization under two-tone and LTE-like modulated excitations with 10-MHz and 100-MHz instantaneous bandwidth shows that the conventional linear-efficiency trade-off in bias design does not necessarily hold true for wide instantaneous bandwidths. Additionally, techniques to synthesize a negative baseband impedance using low frequency feedback are discussed.