A monolithic capacitive transducer for electrical capacitance tomography

Abstract

This thesis presents a new high-resolution, fully-integrated monolithic capacitive transducer for portable electrical capacitance tomography (ECT) applications. This mixed-signal chip comprises a new switched-capacitor (SC) capacitance-to-voltage (CV) convertor with a stray immunity, a new offset-reduced chopping differential difference amplifier (DDA) for post amplification and a digital control module for generating a series of control clocks. The CV convertor, being a critical building block, adopts correlated double sampling (CDS) to minimize the 1/f noise and cancel the dc offset arising from the dedicated op-amp having a high power-bandwidth efficiency. Moreover, it realizes a new instrumentation-based methodology through additional auto-zero (AZ) operations to sample and cancel the front-end circuit level switch errors.