TIMEBASE CALIBRATION METHOD FOR AN EQUIVALENT TIME SAMPLING DIGITIZING INSTRUMENT

A method of calibrating a timebase in a digitizing instrument estimates the frequency of the clock signal from the clock generator that clocks a coarse delay counter in a strobe generator. The dynamic range of the interpolator in the strobe generator is defined in digital-to-analog converter code values as a function of the clock signal period. A linear horizontal look-up table of equally spaced digital-to-analog converter code values is generated over the defined dynamic range of the interpolator. Residual nonlinearities of the interpolator over the defined dynamic range of the interpolator are characterized and scaled to digital-to-analog converter code values. The digital-to-analog converter code values of the characterized residual anomalies are combined with the digital-to-analog converter code values of the linear horizontal look-up table to generate a horizontal look-up table having DAC code value compensating for the nonlinearities of the interpolator.