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 (fmax) 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 (fmax=12 GHz), 4.6-mm long (fmax=50 GHz), and 3.12-mm long (fmax=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 fmax=12 GHz, 1.16 dB for fmax=50 GHz, and 2.65 dB for fmax=110 GHz. The MEM beams are actuated using high-resistance SiCr bias lines with typical actuation voltage around 30-45 V

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