A new method for the differential gain and phase measurement of ADC

We propose an original numerical method to measure the differential gain and differential phase. One usually uses an NTSC video signal. These parameters are defined as the difference of gain or phase between two successive video signals. In our CANPCI system, based on data processing with a computer, analog methods are impossible to implement. That is why we have developed a new numerical method. This method uses a dual-tone signal: a small HF signal in amplitude coupled with a strong LF signal. We determine the parameters by using algorithms based on envelope detection for the differential gain and synchronous detection for the differential phase. We give as an example the results obtained with the AD775 from Analog Devices.