Optimized designs of piezoelectrically actuated MEMS Varactors for microwave applications

The objective of this work is to present superior mciromachined Varactors with better performance than their CMOS counterparts. This paper presents design and simulation of novel piezoelectrically actuated Micro Electro Mechanical Systems (MEMS) Varactors for microwave range of frequencies with lower actuation voltages, higher tuning range and excellent quality factor. Various models have been designed and simulated with using Lead Zirconate Titanate (PZT), Aluminium Nitrate(AlN) and Zinc Oxide (ZnO) as the piezoelectric material. The Varactors have been simulated using Coventorware^™ while the Radio Frequency (RF) characteristics are extracted using ANSOFT High Frequency Simulation Structures (HFSS). The simulations show that the actuation voltages required for these Varactors was lower than 3.5 Volts. The Tuning Ratios (TRs) for these Varactor structures ranges from 7:1 to 20:1 across the four designs. The quality factor obtained for these Varactors is also commendable with values as high as 500.