1149.4 std

Abstract:
The testability structure for digital circuits described in IEEE Std 1149.1-1990 has been extended to provide similar facilities for mixed-signal circuits

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introduction

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1. Overview
1.1 Organization of the standard

1.2 Context

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In Figure 1, the component that is the subject of this standard is shown shaded. In a typical mixed-signal analog and digital PCA,

The PCA is tested, both in production (to verify correct manufacture) and in field service (to detect and locate faults), using automatic test equipment (ATE) to supply test signals to, and to collect test responses from, some or all of the component pins.

1.3 Scope of the standard
1.3.2 Interconnect testing
1.3.3 Parametric test
The second objective of this standard, parametric test, recognizes the fact that groups of one or more discrete components are often interposed between integrated circuits, performing functions such as level shifting, passive filtering, and ac coupling.

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Also illustrated in Figure 3 is an example of differential interconnect, which is a pair of pathways carrying signals whose information content is defined by the pair of signals rather than by either one signal individually.

A similar situation from the testing point of view is illustrated in Figure 4, where an analog signal to be transmitted is passed through an analog-to-digital converter, transmitted as a parallel set of digital signals, and passed through a digital-to-analog converter to form a received analog signal.