CMOS Current-Frequency Signal Processing Unit for Bioimplantable Sensors

Over the past few decades, implantable monitoring of glucose, lactate acid, and pH monitoring has become a viable replacement for stationary monitoring. Implantable biosensing requires biosensors in conjunction with corresponding potentiostats and a signal processing unit to translate the data information to a more versatile, transmittable form. This thesis presents a current-mode signal processing unit (SPU) that merges the simplicity of a charging capacitor in feedback topology with the accuracy of a delta-sigma modulator to create a pulse train with a frequency proportional to the input current. The SPU was realized in a 0.18 µ[micro]m bulk CMOS process.