Architecture and Cell Design of the IISIC CMOS-Chip serving as a Front-End for Integrated Impedance Spectroscopy

Impedance Spectroscopy and related methods has established itself as a highly capable, versatile, and increasingly applied method in the sensor, measurement, and instrumentation community. Applications are ranging from the wellknown characterization of electronic devices' properties, the analysis of chemical substances presence and quantity, cell and tissue measurement in bio-medical applications or in food analysis and food safety tasks, to the improved reading and diagnose of diverse sensors. The application spectrum imposes very diverse constraints on the measurement set-up with regard to impedance, frequency, DC/AC current, and voltage range, as well as measurement speed, cost, and equipment size. State-of-the-art desktop equipment meets the functional needs, but is too big and costly. Embedded solutions on PCB-basis have been conceived with interesting properties and medium size and effort. Commercial chips, e.g., the AD5933, open the door to small hand-held, mobile devices, but it unfortunately quite restricted in its frequency range and other parameters. In this work, an CMOS-IC approach to an integrated impedance spectroscopy system is presented, that will offer digital programmable AC current from 0.325 muA to 1020 muA, with separately programmable DC-Offset, and a range of approx. 20 Hz-3.25 MHz for impedances of about 1 Omega to ~8 MOmega. These specifications allow tackling of numerous relevant applications, as e.g., biomedical tasks or food analysis in ISE Lab-on-Spoon project.