Applications of Linear Modeling to Testing and Characterizing D/A and A/D Converters

Download or read book Applications of Linear Modeling to Testing and Characterizing D/A and A/D Converters written by Carsten Wegener and published by . This book was released on 2003 with total page 173 pages. Available in PDF, EPUB and Kindle. Book excerpt: Data converters are a particularly important class of mixed-signal circuit. Their performance improves with time, driven by market forces leading to developments in design and manufacturing processes. Device testing, however, is becoming a bottleneck as available tester resources are limited in terms of accuracy when test time is limited. Model-based testing has been proposed to address this problem. In chapter 2 of this thesis, we demonstrate model-based testing for a 12-bit DAC, following an algorithm originally proposed by the National Institute of Standards and Technology (NIST), which marks the starting point of the work. We identify shortcomings with the NIST algorithm and open questions that are addressed in the remainder of the thesis. Based on the experience with DAC modeling, we apply our refined modeling procedures to a 12-bit ADC in Chapter 3. For this device, we demonstrate advantages and discuss trade-offs when model-based testing is applied in a production test environment. In a trial run, testing two wafer lots of devices, the robustness of the model is demonstrated in the presence of significant manufacturing process drifts. The choice of test conditions is discussed in Chapter 4. Experimental evidence is given that a test condition which yields more precise model parameter estimates is advantageous. In the example, the same condition is used for another test performed on the devices; thus, measurements can be shared between both tests. The idea is taken further towards Design-for-Testability considerations and towards Design-for-Test, reducing measurement accuracy limitations that are encountered for high-resolution data converters. In Chapter 5, test point selection strategies are discussed. In particular, structural faults are considered, and a novel test point selection algorithm is developed to cover hard-faults. This algorithm yields a single set of test points that provides hard-fault coverage as well as serving the model-based device parameter extraction that is a cornerstone of the test effort reduction technique based on linear modeling. In Chapter 6, we apply the modeling techniques developed previously to characterize the influence of the manufacturing process on device performance. In this application, we exploit design information that was used to form the a priori model. Certain types of design changes can be accommodated in this model and the performance of a re-design can be predicted. We consider re-sizing of circuit elements and digital calibration techniques as examples of possible re-designs.