A Single-Ended Phase and Impedance Invariant mm-Wave VGPA Based on Shunt CS-CG Topology

A novel single-ended variable gain power amplifier (VGPA) topology, named as shunt Common Source-Common Gate VGA, is introduced in this article. A fundamental building block as CS-CG Unit (SGU) is proposed to provide gain tuning function with a sufficient dynamic range. Some valuable characteristics of a single unit are elaborated and then utilized to finally compose a VGPA for compact 5G phased array applications. A prototype VGPA is taped out in commercial 65nm CMOS process as an experimental verification of such theory. Satisfying measurement results are obtained with an absolute bandwidth ranging from 22.6 to 37GHz (fractionally 48.3%) and a gain dynamic range of 12.8dB among which phase variation remains less than 4.8 $^{\circ}$ . Furthermore, the output 1-dB compression point is measured to be around 12dBm at several in-band frequencies. Benefiting from the full single-ended configuration, the footprint shrinks to a large extent as the circuit occupies only 0.11mm².