2019 Symposium on Design, Test, Integration & Packaging of MEMS and MOEMS (DTIP) | 2019
Process-Voltage-Temperature Analysis of a CMOS-MEMS Readout Architecture
Abstract
Thermal drift is one of the main issues limiting the performance of resonant MEMS sensors. Their impact may be minimized at several levels, such as specific system-level solutions (e.g. differential sensing) or mechanical design (e.g. privileging suspended structures). While solving these issues is essential, one should not overlook the temperature-dependence of the readout and oscillation-sustaining electronics associated to the resonators. Considering monolithic CMOS-MEMS devices, thermal drift of the electronics becomes the main challenge, when off-the-shelf building-blocks are used over a large temperature range (from −40°C to 175°C). In this paper, a process-voltage-temperature analysis of electronics readout is carried out to illustrate this issue. Proposed analysis shows that the phase-difference between the motional signals decreases monotonically with temperature. In extreme voltage-temperature conditions for 3σ variability, phase-difference achieves −7.2° at 175°C, VDD−= 1.62 V; and 5° at −40°C, VDD = 1.98 V. This result highlights the need of CMOS / MEMS co-design and optimization tools, for improving the thermal stability of resonant sensors in high-end, extreme environments such as automotive applications.