Title :
Differential piezoresistive sensing in a bulk-mode micromechanical resonator
Author :
Xueyong Wei ; Seshia, Ashwin A.
Author_Institution :
Dept. of Eng., Univ. of Cambridge, Cambridge, UK
Abstract :
A report is presented on a differential piezoresistive sensing approach for transducing the motional response of bulk-mode micromechanical resonators. High-frequency bulk-mode micoresonators have inherently high stiffness and demonstrate limited range of motion, which in turn presents challenges for the capacitive sensing method in the presence of large parasitic feedthrough. A differential piezoresistive sensing approach is implemented in this Letter to substantially reject the effects of parasitic capacitive feedthrough, leaving the response recovered directly from the measurement. With differential pick-up, a 33 dB drop of feedthrough has been achieved and a resonant peak magnitude of 14 dB is obtained for a drain current of 1 mA, which is shown to be approximately 20 times higher than that obtained for the conventional piezoresistive sensing scheme. This method also enables a low DC voltage for capacitively driving the bulk-mode resonator. As an example, a resonant peak magnitude of 5 dB is demonstrated using 3.55 mA drain current and 5 V DC driving voltage.
Keywords :
capacitive sensors; micromechanical resonators; piezoresistive devices; bulk-mode micromechanical resonator; capacitive sensing method; current 1 mA; differential pick-up; differential piezoresistive sensing approach; drain current; feedthrough drop; gain 33 dB; large parasitic feedthrough; motion range; motional response; parasitic capacitive feedthrough effects; piezoresistive sensing scheme; resonant peak magnitude; stiffness; voltage 5 V;
Journal_Title :
Micro & Nano Letters, IET
DOI :
10.1049/mnl.2012.0789