A Ka-Band Gm-Boosted PS-VGA With Low Phase Variation by Main-Path Inductor Compensation

A vector-summing phase shifter (VSPS) with gm-boosted structure followed by a variable gain amplifier (VGA) with low phase variation, i.e., PS-VGA, was demonstrated at 27–31 GHz. Triple-coupling transformer (TCT) technique was employed in VSPS for gm boosting and noise reduction. A novel phase compensation technique of main-path inductor compensation (MPIC) was proposed in VGA to greatly suppress the phase variation by mitigating the impact of OFF-state drain–source capacitance (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${C} _{\text {ds-}\text {OFF}}$ </tex-math></inline-formula>). The fabricated PS-VGA in 65-nm 1P9M CMOS technology has achieved a 360° phase shifting range with 6-bit phase resolution and a 15.5-dB gain range with 0.5-dB gain step. The measured root-mean-square (rms) phase error for VSPS is 0.46°–1.58°. The measured rms gain error for VGA is 0.06–0.11 dB along with a phase variation of less than 3.85°. To the best of our knowledge, the measured phase variation is the lowest one for VGA with a wide gain range (>15 dB). The total power consumption of PS-VGA is 28.0 mW.