Optimization and Implementation of Impedance-Matched True-Time-Delay Phase Shifters on Quartz Substrate

In this paper, design equations for true-time-delay microelectromechanical (MEM) phase shifters comprised of impedance-matched slow-wave unit cells are presented. The input to these equations requires only the specification of the maximum frequency of operation (f_max) and substrate dielectric constant (epsi _r). The basis of the design methodology is to maximize the phase shift versus insertion loss performance. Experimental data for three 1-bit devices that are 11.44-mm long (f_max=12 GHz), 4.6-mm long (f_max=50 GHz), and 3.12-mm long (f_max=110 GHz) shows a maximum phase deviation of 3% compared to predicted performance, with S₁₁ less than -19 dB from 1 to 110 GHz. The worst case insertion loss is 0.9 dB for f_max=12 GHz, 1.16 dB for f_max=50 GHz, and 2.65 dB for f_max=110 GHz. The MEM beams are actuated using high-resistance SiCr bias lines with typical actuation voltage around 30-45 V