A 130 GHz 360⁰ Gain-invariant Phase Shifter with 5.625⁰ Phase Resolution, 0.19⁰ 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 5-bit phase-invariant variable gain amplifier (VGA) in a 130 nm 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 phaseinvariant VGA ensures phase invariance by introducing capacitor at the common-base transistor and inductor between the commonemitter 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 phaseinvariant VGA achieves a gain control range of 5.5 dB.