Predicting performance parameters of analog and mixed-signal circuits using built-in and built-off self test
The widespread use of embedded mixed-signal cores in system-on-chip (SoC) or System-on-Package (SoP) design has been increasingly important in cost-effective manufacturing test for mixed-signal devices. A typical SoP encapsulates many of its internal functions, and its production test is performed by application of test signals to the SoP under control of external Automatic Test Equipment (ATE). However it is a problem that the external ATE does not have direct access to all the internal embedded functions of the SoP. Thus a classical test approach to SoP suffers from limited controllability and observability of its subsystems. Built-in Self-Test (BIST) and Built-off Self-test (BOST) schemes have been suggested and developed to overcome the limitations of conventional test, such as limited test Input/Output (I/O) accessibility as well as high test cost. However most BIST/BOST approaches have limited test accuracy. The focus of the dissertation is to develop a cost-effective performance-based test methodology based on BIST/BOST, while maintaining the same accuracy as conventional test. This dissertation proposes one BIST approach and two BOST schemes. Our BIST methodology presents a methodology for efficient prediction of circuit specifications with optimized signatures. The proposed Optimized Signature-Based Alternate Test (OSBAT) methodology accurately predicts the specifications of a Device Under Test (DUT) using a strong correlation mapping function. The approach overcomes the limitation that analytical expressions cannot precisely describe the nonlinear relationships between signatures and specifications. Our first BOST approach presents a practical methodology for effective prediction of individual dynamic performance parameters of differential devices with a cascaded Radio-Frequency (RF) transformer in loopback mode. The RF transformer produces differently weighted loopback responses, which are used to characterize the DUT dynamic performance. The approach overcomes the imbalance problem of Design for Test (DfT) circuitry on differential signaling, thereby accurately measuring the dynamic performance of differential mixed-signal circuits. The second BOST scheme is an efficient methodology for accurate prediction of aperture jitter using cost-effective loopback methodology. Aperture jitter is precisely separated from input and clock jitter as well as additive noise present in the DUT, by using an efficient loopback scheme. Hardware measurements were performed for all our approaches, and good results were obtained. This fact verifies that all approaches can be practically used for production test in industry.