Analog to digital convertor with drift compensation.

摘要

An analog to digital convertor (20) comprises an amplifier (100) for amplifying an analog input signal to generate an amplified output signal. Conversion means (110) periodically samples the amplified output signal to generate a digital word as a function of each sample. Compensation means preferably including a microcontroller logic circuit (130) compensates for a drift in the output signal steady state level of the amplified output signal. The compensation means includes tracking means (130) for summing a digital offset value and the digital word in response to and to compensate for the drift in the output signal level between upper and lower limits. The compensation means also includes bias means (130,140) for changing a bias signal level at the input of the amplifier (100) in response to and to compensate for the drift extending beyond the limits. The compensation means further includes logic means (130,190) for modifying the digital word in response to and to compensate for the step change.