The Researches On Mixed-Signal Test And Design For Testability

With the rapid development of microelectronic technique,integrate circuit and system become more and more complex.Traditional test models and test methods are not competent for the times'require on account of the gigantic test expense.In the field of AMS(Analog Mixed Signal),due to the circuit form and peculiarity of the signal,test theory falling behind relatively.Especially present,Soc(System on chip) design and deep sub-micron process have brought the new problem.Test will be the bottleneck of development of SOC system.The theory and technology of testing and testable design have become an important research direction in VLSI field,and it is much more valuable in theory and practice.This paper starts with the basic testing theory and method,and then gets a more deep research into the testability of system level mixed-signal chip.First,analysis of the system level chip testability is started from the basic fault model,and a primary analysis is made on fault classification,fault simulation,test generation and algorithm. Then a deeper research is made on testability of design,including Ad hoc design,scan test,boundary scan test,build-in self-test.An example is also proposed to demonstrate BIST based on FPGA,including modules of test pattern generator,kernel circuit under test and feature analyzer.To demonstrate the correctness and efficiency of BIST,a fault is injected into a normal circuit,and then a simulation is performed on both the normal circuit and the circuit with fault injection.A special discussion on testing the mixed signal circuit is performed,and a comparison is carried out on the simulation strategy between analog circuit and mixed signal circuit to illustrate the difficulty in designing and simulating the mixed-signal circuit.Also,an introduction to the VHDL-AMS language is made,which is used to describe mixed signal design and its simulation, and the paper is also pointed out the basic design flow using VHDL-AMS and the extended new concept of VHDL-AMS.The application of IEEE1149.4 standard of mixed signal test bus in VLSI is also introduced.At last,the paper introduces the mixed signal test theory based on DSP.The paper also presents the hardware and software design of the auto test equipment based on DSP which can be used to test integrated circuit and PCB board. In conclusion,the design method of testability for mixed-signal chip with lower cost,higher fault coverage and higher reliability is the demand of further development of system level chip.