Background

At present, most part of the signal processing performed in electronic systems is becoming digital, and the role of the analogue- to-digital converters (ADCs) placed at the borders of the digital domain acquires a particular relevance, since the signal degradation introduced by these components cannot normally be recovered by subsequent processing. Both the markets of stand-alone ADCs and of ADC macrocells to be embedded in complex ASICs, would take benefit from the availability of performance parameters accurately describing the expected behaviour of the ADC and of clearly specified test methods for their measurement.

At present, however, the standardization of ADC test procedures is not so well developed. In particular, IEC 60748 covers only quasi-static operation, while IEEE Std 1057 deals with dynamic testing but, being addressed at digital waveform recorders requires some adaptions to cover ADCs. An IEEE committee is presently developing a new standard, 1241, specifically aiming at ADCs.

Objectives

A first aim of this project is to contribute to the improvement of the European rules concerning the test methods for ADCs, by proposing an integration to IEC 60748 concerning the parameters specifying the dynamic behaviour of the ADC, the measurement conditions, and the data processing algorithms.

A second aim is to investigate and propose new test methods to circumvent the limits of the measurement instrumentation, which is strongly challenged by today's high resolution, high speed converters. Techniques for the measurement of parameters required by specific applications (e.g. audio hi-fi) and for the debugging of new converter designs will also be investigated. Dissemination of the knowledge gathered during the activity is the third objective. A book explaining the meaning and relevance of ADC specification parameters, and the related measurement techniques will be prepared, to provide guidance in the selection of components and of test methods.

Work programme

The first workpackage addresses a number of open questions concerning the implementation of the "classical" dynamic test methods based on the application of a sinusoidal stimulus to the ADC under test. The problems related to the use of automatic test equipment (ATE) suitable for low-cost, volume testing will be considered. The effectiveness of the various methods will be compared, and a draft norm on the dynamic characterization of ADCs using sinusoidal stimulus will be prepared. The measurement of other dynamic parameters which do not require a sinewave input (e.g. sampling jitter, whose measurement poses critical demands on the measurement instrumentation), and more generally of parameters required by specific applications (e.g. video or digital audio) is covered by the second workpackage.

The third workpackage includes longer term research activities, such as the definition of new global performance parameters, the development of new procedures for test and diagnosis, sample and hold characterization.