Design, fabrication and characterization of compact 4-bit RF MEMS capacitor bank in standard CMOS 0.35μm process

This paper reports on the design and fabrication of a 4-bit switched capacitor bank designed to operate over the frequency range of 3-10 GHz with a tuning range of up to 10:1. An optimized mask-less CMOS post-processing technique is used to fabricate the 0.6 mm × 0.9 mm capacitor bank. We propose a procedure employing dry etching with cryogenic cooling to tune the residual stress in the beams. The capacitor is analyzed both theoretically and experimentally. The analysis of the measured value ~ 5 of Q suggests an approach to enhance the capacitor's Q. The measurement demonstrates the 16 different states covering the range of 0.15-1.2 pF with no sign of self-resonance up to 10 GHz.