A 10 bit interface circuit for an array of capacitive transducers

Terahertz Cameras are going to be widely used in many places, specifically for medical purpose and there are many advantages over the use of terahertz signals for imaging. Among different methods of terahertz imaging, the transformation of the THz signals into the form of absorbed heat and mechanical displacements can be used for medical purposes. The use of mechanical deflections for cameras requires a method for measuring the displacement. From different modalities for displacement sensing, capacitor based displacements are widely used in literature. For many reasons, including cost and feasibility with current technologies and compatibility with MEMS fabrications process, capacitive displacement transducers are the best choice for photo-mechanical cameras. Simulations show that the interface circuit should satisfy a sufficiently good safe margin for operation of circuit in different sensing capacitor dimensions. A rail-to-rail voltage at the output of the sensor interface circuit might limit tolerance of the fabrication process. Therefore, conventional method with limited output voltage swing is employed to provide sufficiently flexible solution. A 10 bit data converter transduces the capacitance value to a digital modulated signal.