The IEEE 1149 4 standard for a mixed-signal test bus (Dot4) [1], which addresses the application of boundary- scan test techniques in mixed analog / digital circuits, was adopted already in 1999 However, major electronic manufacturers, with few exceptions [2], do not seem very keen to include Dot4 support into their products It is our belief that wider acceptance of Dot 4 mixed-signal test bus will only come with the demonstration of its benefits in actual designs and the presentation of innovative and efficient applications of the Dot 4 infrastructure [3, 4] To support development and evaluation of Dot4 based test and measurement procedures we decided to design and implement a series of experimental Dot 4 chips to serve as technology demonstrator vehicles