A 130 GHz 360° Gain-invariant Phase Shifter with 5.625° Phase Resolution, 0.19° RMS Phase Error and < 0.56 dB 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 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 and inductor at cascode amplifier. The proposed PS achieves a measured minimum RMS phase error of 0.19° at 130 GHz and < 2.63° over 125.3 - 144.2 GHz for the first time. The measured RMS gain error is less than 0.56 dB over 125.3-144.2 GHz. The phase-invariant VGA achieves a gain control range of 5.5 dB.