Circuit Implementation Enabling Full-Scale Linear Sensing in Mode-Localized Sensors.

Weakly coupled resonators (WCRs) predicated on the mode localization phenomenon have found widespread utility in the topological design of high-performance sensors. However, the pronounced non-linearity derived from the loci veering around the zero point imposes a significant constraint on the measurement range of mode-localized sensors. This paper introduces a novel single-port readout circuit aimed at realizing full-scale linear sensing for mode-localized sensors. In our proposed methodology, we employ not only the conventional frequency closed-loop control but also introduce an amplitude closed-loop system incorporating automatic gain control (AGC). This AGC-based approach is utilized to maintain the amplitude product of resonant units at a standardized value. Consequently, we can consider the difference of squared amplitudes as the sensor output, which serves to effectively capture and characterize the fluctuations in external input signals. Furthermore, we have applied our proposed readout circuit to test a prototype of a micro-electro-mechanical system (MEMS) mode-localized accelerometer. The experimental results unequivocally affirm that the tested accelerometer prototype achieves linear sensing throughout the entire measurement range. Remarkably, it demonstrates a mechanical sensitivity of 0.1182 /g, coupled with a maximum non-linearity of -6.54%, and a bias stability of 19.23 mg, alongside a noise floor of 1.022 × 10 ^-4 V/Hz ^1/2 . These outcomes align closely with the output metric based on the subtraction of reciprocal amplitude ratios (SRAR). Our proposed methodology not only facilitates full-scale linear sensing for mode-localized sensors but also streamlines the signal extraction process, all while preserving the electromechanical performance. This advancement holds significant promise for the expansion of the application landscape for mode-localized sensors.