| 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 &Sgr;-&Dgr; 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 &Sgr;-&Dgr; loop, and hence, limit the applicability of &Sgr;-&Dgr; technique to such sensors. A solution is provided that allows stabilizing the &Sgr;-&Dgr; loop, in the presence of high-Q parasitic modes. The solution is applicable to low or high order &Sgr;-&Dgr; based interfaces for capacitive sensors. |
