The test of Sigma-Delta Analogue-to-Digital Converters (?? ADCs) is a difficult task due to the high resolution and the large number of samples required. By integrating an additional test circuitry in the chip and by taking advantage of the resources already existing in a ?? ADC, it is possible to perform a Built-In Self-Test (BIST) technique to make the converter auto-testable. In this paper we present an approach for both the on-chip test signal generation and the on-chip output response analysis. The method, mostly digital, is based on the application of a binary stream which encodes a sinusoidal signal. This stimulus is chosen to have a very high quality in the bandwidth of interest of the converter with the quantization error laying out of the analogue modulator bandwidth. In order to analyse the output response, we need a very precise sinusoidal signal. This reference signal can be also obtained from the same input stimulus, by passing it directly to the digital filter existing in the converter. Simulations results show the capability of this technique to obtain measures of the SNDR (Signal-to-Noise-plus-Distortion Ratio) for a 16-bit audio ?? ADC.
A digital bist for a 16-bit audio sigma-delta analogue-to-digital converter