Asynchronous Time-domain Amperometric Sensor Interface For a Wide Range of Cdl

The linearity and stability of an amperometric sensor can be affected by the size of the double layer capacitor (
$C_{dl}$
) in the electrode. A working electrode (WE) with millimetre size area can have a
$C_{dl}$
larger than 10nF, whereas a WE in nanometer range show tens of femto-Farad
$C_{dl}$
. We propose an amperometric sensors that is immune to the negative effect introduced by a wide variance of
$C_{dl}$
, but does not require and additional mismatch calibration. By using dynamic current mirrors, the resolution of the sensor is increased to over 9bits. We perform extensive simulation to determine linearity (
$R^{2} > 0.999$
), DNL and noise floor all within acceptable limits.