Title: Method of improving analog comparator calibration accuracy
Abstract: Product performance specifications often require monitoring of signal lines for minimum and maximum dc levels and pulse amnplitudes. Monitoring is usually done on a Go/No-Go basis since a recorded value is not required. This type of signal monitoring can be done with an analog-type voltage comparator. The integrated circuit analog voltage comparator is widely used in this application since it is both accurate and economical. The accuracy of the voltage comparator will depend on the accuracy of the instrumentation used in setting the comparator threshold level (limit value) and the comparator threshold stability. The threshold stability can be determined by reconding the as-found threshold level during the calibration check. A closed-loop ramp-generator calibration technique has been developed to provide digital-voltmeter readout of the comparator threshold level. The as-found comparator threshold level is automatically determined during the calibration check when this calibration technique is employed. This technique minimizes the time spent in conducting the calibration and provides an accurate measurement of comparator hysteresis. (auth)