An organization of the test bus for analog and mixed-signal systems

System level solutions for error detection in analog and mixed-signal circuits are presented in this paper. Internal blocks of an analog circuit are accessed using a technique similar to the boundary scan organization. Test points are controlled by a digital control signal scanned into a system, and the test signal and test results are connected to an analog test bus. Analog response can be verified either on-line without interruption to the signal path, or in a test mode. No new elements (like virtual or real switches) are added to the signal path. As a result the proposed test bus can be easily incorporated in the existing designs as an add-on feature enhancing system testability