Patent ID: 8497729
Filing Date: 2013-07-30
Classification: G01R,H03K,H03M

Abstract:
1. A time-differential analog comparator, comprising: a variable frequency signal source coupled to provide a repeating signal having a plurality of periods, wherein each period has a frequency corresponding to a value of an analog input; a timing circuit coupled to define a timing sequence including a first time interval and a second time interval, wherein the timing circuit begins the timing sequence in response to a begin compare signal and ends the timing sequence in response to a timing complete signal, and wherein the timing circuit generates a mode select signal at a time between the first time interval and the second time interval to stimulate a change in the analog input; a counting circuit coupled to the timing circuit to count the periods of the repeating signal, wherein the counting circuit is a bidirectional counter coupled to count in a first direction for the first time interval and coupled to count in a second direction opposite to the first direction for the second time interval that starts after an end of the first time interval, wherein the counting circuit generates a count-up signal and a count-down signal and outputs a digital count signal; and an evaluation circuit coupled to the counting circuit and the timing circuit, wherein the evaluation circuit generates a decision signal in response to a count of the periods of the repeating signal indicated by the digital count signal after an end of the second time interval, wherein the first time interval is not equal to the second time interval to generate an offset in the decision signal.