Built in self-test

Abstract

A method for testing a DAC comprising controlling the DAC digitally to cause it to produce a known desired analogue output, for example a fixed amplitude sine wave; determining the duration of fixed voltage segments of the actual output of the DAC and using the duration of the fixed voltage segments to assess or determine performance of the DAC.

1 . An active flicker noise cancellation method for correcting flicker in an analog output of a DAC, the method comprising measuring variations in a point in a repeating signal (a cyclo-stationary point) and applying a correction to an input code of the DAC to cause correction of the output. 
     
     
         2 . The method as claimed in  claim 1 , wherein the step of measuring the variations in the cyclo-stationary point comprises using a chopper stabilized comparator circuit. 
     
     
         3 . An active flicker noise cancellation technique for correcting flicker in an analog output, the method comprising measures variations via sampling in a cyclo-stationary point to generate, and applying an opposing correction signal to the analog output. 
     
     
         4 . The method of  claim 3 , wherein said sampling comprises capacitive sampling.