System for difference calculation using a quad slope converter

摘要

A system for measuring signals in a non-linear network is provided which reduces the reliance on hardware and processing support when correcting for A/D offset by performing a pair of dual slope measurement cycles with an integrating analog to digital converter (ADC) circuit. Each of the measurement cycles has at least four phases including a first integrating phase and a first de-integrating phase followed by a second integrating phase and a second de-integrating phase. The system further includes an ADC controller operatively communicative with the integrating ADC circuit for detecting when the first count value is reached during the second de-integrating phase and then resetting the second count value in response to this detection so that the second count value is offset corrected at the end of the second de-integration phase. As a result, a difference calculation is automatically performed during the measurement cycle.