A 130GHz 360° Gain-Invariant Phase Shifter with 5.625° Phase Resolution, 0.19° RMS Phase Error and < 0.56dB RMS Gain Error

This paper presents a D-band gain-invariant phase shifter (PS), integrating a 6-bit vector-modulated based active PS and a 5-bit phase-invariant variable gain amplifier (VGA) in a 130nm SiGe BiCMOS technology. To minimize gain and phase errors of the PS, a Lange coupler with high characteristic impedance for the coupling line is employed as the I/Q generator, ensuring < 0.1 dB amplitude and < 1.50° phase imbalances. Additionally, phase-compensated lines are incorporated into the phase-inverter-embedded variable gain amplifier (PI-VGA) to mitigate phase fluctuations at different gain levels. The phase-invariant VGA ensures phase invariance by introducing capacitor at the common-base transistor and inductor between the common-emitter and common-base stages. The proposed PS achieves a measured minimum RMS phase error of 0.19° at 130 GHz and < 2.63° from 125.3 to 144.2 GHz for the first time. The measured RMS gain error is less than 0.56 dB over 125.3–144.2 GHz, and the measured peak average gain is 10.6 dB at 131 GHz. The phase-invariant VGA achieves a gain control range of 5.5 dB.