A frequency stability analysis and design method for frequency robust resonators, such as MEMS resonators, is presented. A selected button of the button circuit serves as a last-button-pushed display button that can be pushed to read the memory unit and show the last button pushed via the display. The method can further include providing an air delivery tube configured to receive pressurized air. The middle portion of the bridge is bonded to the substrate to provide a compressed crystalline semiconductor layer on the substrate. The conductive substrate and plurality of bond pads function to provide electrostatic shielding to the MEMS structure. The adjustable rim is adjustable between a first configuration in which the rim defines an opening with a first diameter, and a second configuration in which the opening of the rim defines an opening with a second diameter different than the first diameter.