Experimental and finite-element study of convective accelerometer on CMOS

Abstract

This paper addresses the design of CMOS thermal accelerometers. A test-chip including the sensor and a signal conditioning circuit has been designed, fabricated and characterized. The obtained sensitivity is 375mV/g while resolution is estimated at 30mg. This test-chip is used to improve the modelling of heat transfer phenomenon in theses devices. FEM is successfully used as a first modelling approach.

Noise analysis of a first-order thermal ΣΔ architecture for convective accelerometers

“…where S(K) is a fitting coefficient (extracted from FEM analysis and experimental results) representing the system sensitivity, a (m s -2 ) is the acceleration, q (kg m -3 ) is the gas density, b (K -1 ) is the gas coefficient of expansion, l (kg m -1 s -1 ) is the gas viscosity, l (m) is a linear dimension related to the cavity volume and geometry and s (s) is the time constant of the fluid (s = 0.5 … 12 ms, depending on the cavity geometry and dimensions [9]). Finally, Sect.…”

“…Many studies report the design and optimization of openloop convective accelerometers [1][2][3][4][5][6][7][8][9][10] but very few of them address the conditioning electronics as a solution to improve the system overall performance. In most of the previous works, an open-loop and continuous time read-out circuit is used on the basis of a simple instrumentation amplifier.…”

“…• The thermal inertia of the detectors which limits the bandwidth of the sensor to several tens of Hertz. It was previously demonstrated that bandwidth higher than 100 Hz could be reached through a reduction of the volume of the cavity, making thermal inertia of detectors the limiting factor [9].…”

Investigations on electrical-only test setup for MEMS convective accelerometer

“…This voltage is then amplified by an instrumentation amplifier (A1, G=100) based on standard operational amplifiers from the foundry design kit. Detailed information concerning the sensor manufacturing, modeling and experimental results can be found in previous publications from the authors [9][10][11]. The main drawback of this sensor was found to be the detectors' thermal inertia that limits the sensor bandwidth to few tens of hertz.…”

Absolute pitch, roll and yaw measurement on CMOS

“…FEM simulations (static and transient) have also been developed to study the influence of design parameters on the performance [5]. FEM analysis also supports the development of compact models for system level design.…”