Wide-range, high-accuracy signal-processing unit for implantable potentiostats

A new signal-processing unit (SPU) for implantable biomedical sensors is proposed. The proposed scheme combines the advantages of the two main structures of conventional SPUs (delta-sigma modulator and charging capacitor in feedback). The preliminary design has been realised in a 0.35 m CMOS process. Test results validate the desired functionality of the system. In this reported work an additional modification to the SPU is proposed to facilitate simple frequency modulation. Simulation results in the same process confirm the linearity of the system corresponding to a wide range of sensor currents.