Testing high frequency adcs and dacs with a low frequency analog bus

As the sampling frequency of new ADCs and DACs increases, it gets more dificult to accurately convey the analog stimulus or response to or from the converter under test - there is a bandwidth bottleneck. This paper describes a technique that uses a 400 kHz analog bus, such as the standard 1149.4 bus, to convey an arbitrary analog signal, and converts the signal to or from a high frequency at the converter, on-chip. This permits existing low-frequency distortion tests, both ATEbased and embedded, to be used for high frequency converters. High frequency noise is easily filtered out, permitting a more repeatable test and the use of low cost testers. A hypothetical 100 MHz, 14-bit ADC and DAC are used as examples. The technique has reduced sensitivity to sampling jitter, and 16-18 bit linearity appears feasible.