CAPACITIVE MICRO-MACHINED SENSOR FORCE-FEEDBACK MODE INTERFACE SYSTEM

摘要

Operating capacitive sensors in force feedback mode has many benefits, such as improved bandwidth, and lower sensitivity to process and temperature variation. To overcome, the non-linearity of the voltage-to-force relation in capacitive feedback, a two-level feedback signal is often used. Therefore, a single-bit - modulator represents a practical way to implement capacitive sensors interface circuits. However, high-Q parasitic modes that exist in high-Q sensors (operating in vacuum) cause a stability problem for the - loop, and hence, limit the applicability of - technique to such sensors. A solution is provided that allows stabilizing the - loop, in the presence of high-Q parasitic modes. The solution is applicable to low or high order - based interfaces for capacitive sensors.