Low loss KU- to KA-band analog DMTL phase shifter with 360° phase shift

A 15 GHz distributed MEMS transmission line (DMTL) based analog phase shifter was designed and characterized. The designed and measured device was capable of full 360° degree phase shift with lower losses than reported for analog DMTL phase shifters. The full phase shift was achieved at 14.6 GHz with a 1.9 dB insertion loss. The achieved figure of merit (FOM) for the device was 188°/dB. Input matching was better than -12 dB across the full tuning range. The varactors loading the coplanar wave guide (CPW) were designed to have a large capacitance ratio by having the actuation electrodes on both sides of the CPW center conductor. The height of the varactor bridge was designed lower above the CPW center conductor to allow for larger capacitance ratio. Approximately a 50 V actuation voltage was required for the full phase shift. The size of the device is 19.4 mm long and 1.2 mm wide. The measured device operation shows the phase shifter can work and achieve the full phase shift of 360° in very wide bandwidth of 15-35 GHz with a FOM above 100°/dB. Even up to 50 GHz the device operates with full phase shift with low losses enabling a FOM above 50°/dB.