Temperature compensation for ISFETs using a floating gate current mirror

Temperature dependence is a of major concern in electrochemical sensing, particularly in on-body applications. We present a low-power temperature compensation topology for an ISFET pixel for pH detection. The design applies compensation to the floating gate using a reference device, whilst retaining the capability to cancel offsets. The compensated pixel designed in a 0.35 μm process significantly outperforms the uncompensated design, with a maximum rate of change -40 pA/°C (-0.13 %/°C) over expected temperature and pH ranges. The power consumption of the reference circuit for a 1.2 V supply is 54 nW.