Mechanical stress measurement electronics based on piezo-resistive and piezo-Hall effects

In the past many circuits based on piezo-resistive structures have been proposed for the measurement of induced mechanical stress drift on the [100] silicon. All of them are affected by thermal errors. In this paper we present a novel measurement scheme based on both piezo-resistive and piezo-Hall sensors. This approach achieves accurate temperature-compensated measurement of σ₁₁, σ₂₂, σ₁₂. Such data are important not only in many mechanical applications but also in some special electronic topics. Particularly, in this case they have been used to make provision for the implemented Hall sensor sensitivity variation due to the package induced stress. A mixed signal circuitry based on an analog high precision multiplexer has been developed to output the many sensor signals to a limited number of external pins. A test chip has been design and manufactured for the austriamicrosystems 0.8 μm CMOS technology and first functional testing has been successfully performed.