Low-noise, temperature-insensitive, voltage or current input, analog front end architecture

摘要

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.