Page 282 - Microsensors, MEMS and Smart Devices - Gardner Varadhan and Awadelkarim

262 MICROSENSORS

The solution to Equation (8.34) is interesting because it has two possible deflections
at certain frequencies. However, running the oscillator at low deflections using closed-
loop feedback avoids this stability issue. The problem with this structure is that the
capacitances for drive and sensing are too low because the microshuttle is only 1 to 5 um
thick. However, recent developments of LIGA and deep RIE now make resonant lateral
structures a practical device. The resonator has now been redesigned by Welham et al.
(2000) to overcome these problems together with a piezoresistive pickup. Figure 8.30(c)
shows the new silicon process and the fabricated device is shown in Figure 8.30(d). These