Wideband millimetre‐wave CMOS power amplifier using transistor‐based inductive source degeneration and specially shielded transformer

Abstract

This study presents integration of transistor based inductive source degeneration and specially shielded transformer into a millimetre-wave power amplifier (mm-wave PA) operating at wideband. A new configuration of high Q distributed inductor is devised and embedded in CMOS transistor source to enhance stability, maximum stable gain and bandwidth of mm-wave CMOS PAs. The source inductance selection is conveniently investigated by the proposed admittance matrix condensation. In power splitting and combining part, a novel X-shape pattern-ground shielding is inserted in high turn ratio transformer to ameliorate wideband matching. Based on these techniques, a fully differential mm-wave PA was implemented in 65 nm low-power CMOS with 0.25 mm2 core area. The measurement results show that its differential drive gain and common mode rejection ratio are above 10 and 26 dB, respectively, in a wide frequency range of 41 to 61 GHz, while the power added efficiency (PAE) is still above 10.8% at 46–62 GHz. This CMOS PA also achieves 11.9 dBm output referred 1-dB compression point (P 1 dB) and 15.2 dBm saturated power (P sat) with 12.4% peak PAE.