Characterization of dynamics in on-wafer RF MEMS variable capacitors using RF measurement techniques

Abstract

In this paper we propose a new system to measure the dynamics of on-wafer RF MEMS variable capacitors -rise and fall times, resonance frequency and damping-, which is based on RF measurement techniques and instrumentation typically available in RF/microwave laboratories. The amplitude of a RF carrier is modulated through the mechanical movement of the MEMS device. This high-frequency carrier is down-converted and detected, extracting the mechanical information from its envelope. This system is designed to measure both, 1-port MEMS capacitors (bias and capacity-testing in the same port) and 2-port extended tuning-range capacitors (bias and capacity-testing in different ports). Another important feature is the possibility of characterizing the dynamics of MEMS devices designed to work at very different operating frequencies in the RF/microwave range because the system is using downconversion and detection at IF. Two MEMS variable capacitors with different actuation principles -electrostatic and electrothermal- are characterized in terms of dynamics using the proposed system.