AFE circuitry handles both voltage and current input signals. In one
embodiment, both a voltage path and a current path are provided from the
input. Switching circuitry selects one of the paths. A switch also turns
on or off a current-to-voltage conversion circuit used to convert a
current input into a voltage. In one embodiment, noise is significantly
reduced by using a dedicated ground pin or terminal for the negative
reference of a differential circuit. This applies the same external board
noise, which is on the input signal, to the negative reference, so the
noise is canceled in the differential signal. In one embodiment,
temperature compensation is provided via an IPTAT circuit which is used
to shift the voltage up in order to balance the decrease in DC voltage
with increasing temperature.