A D-Band 5-Bit SiGe Active Bidirectional Phase Shifter Achieving 0.09-dB RMS Gain Error and 0.86° RMS Phase Error

This paper presents a D-band active bidirectional vector-modulation phase shifter (PS) based on a phase inverter embedded variable gain amplifier (PI-VGA). A Lange coupler and self-shielded Marchand baluns are utilized for IQ signal generation and combination, achieving bidirectional low-loss impedance matching. The switchless bidirectional PI-VGA incorporates compensation networks for parasitic reduction and intrinsic gain enhancement, enabling amplitude modulation and quadrant selection. The PS supports 5-bit 360° bidirectional phase shifting over 112-145 GHz. The measured minimum insertion losses are 7.5 dB and 9.5 dB for forward and reverse operations, with RMS gain errors of 0.09 dB. The measured minimum RMS phase errors for both directions are 0.91° and 0.86°. The measured input 1-dB compression point amounts to 8 dBm and the core area of the PS is only 0.256 mm², with an average power consumption of 81 mW under 3.3 V power supply. To the best of the authors’ knowledge, this is the first reported D-band active bidirectional PS, and the PS is suitable for terahertz time-division duplexing (TDD) phased arrays, offering a compact size and reduced insertion loss.