Precise method for accuracy and sensitivity improvement of a current mirror for very low current measurement on a dissolved oxygen biosensor

Abstract

Abstract Dissolved oxygen measurements using an electrochemical biosensor and conventional current mirror with accurate results and the desired sensitivity are difficult to achieve, though this type of current mirror is used frequently to processbiosensor signals, providing a good response. However, it exhibits some drawbacks particularly due to mismatched transistors, which will lead to asymmetry between input and output currents. This asymmetry causes unwanted offset and gain error, reducing its accuracy, especially at very low current. A modified current mirror utilizing precise gate voltage adjustment of FETs is applied to match the transistors’ currents. The results show accuracy improvement of the modified current mirror compared to the conventional current mirror, where the improvements provide a very low accuracy error of 0.01%. In addition, the current mirror’s sensitivity can be adjusted by implementing this modification without increasing noise significantly.