复旦微电子-专用集成电路设计方法-Dftba.pptVIP

  Design-For-Test Seminar  Design-for-Test Basics Outline Meaning and importance of Design-for-Test DFT terminology Types of tests Fault modeling and detection Test pattern generation Internal scan design Boundary scan design Built-in self-test (BIST) design Yield and Defect Level Testing and Cost Low number of defective parts per million (DPM) is very critical Cost to replace parts grows exponentially throughout design cycle Cost of bad part in critical device (for example, an airplane) is immeasurable! What is Testability? An attribute of a design The ability to create a test program to determine the quality of a manufactured design The combination of a design controllability and observability Controllability measures the ability to control the internal state of the circuit through primary inputs Observability measures the ability to observe the internal state of the circuit through primary outputs What is Design-for-Test? A design methodology that combines design and test to achieve maximum design testability Part of the design synthesis process Necessary due to reduced product time-to-market and advanced technology such as: Synthesis Increasing gate count, with limited increase in I/O pins DFT Strategies Ad Hoc Minimizing redundant logic Minimizing asynchronous logic Isolating clocks from logic Adding internal control and observe points Structured Implies a systematic or automatic approach to increasing design testability Most common method is scan design Built-in self-test (BIST) becoming popular quickly due to the test cost issue, at speed test requirement, and the emerge of intellectual property Types of Test Functional test: Verifying functionality of designs Structural test: Verifying quality of manufactured devices IDDQ test: Verifying CMOS quiescent current of manufactured devices At-speed test: Verifying performance of manufactured devices Parametric test: Verifying AC and DC parameters of manufactured devices Functional Test Verifying functi