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Current Testable Design of Resistor String DACs. Proceedings of the third IEEE international workshop on electronic design, Test and Applications , 2005 指導老師 : 易序忠 班級 :積體碩一 姓名 :黃順和 學號 : 95662009. outline. 1. Introduction 2. Supply current tests of resistor
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Current Testable Design of Resistor String DACs Proceedings of the third IEEE international workshop on electronic design, Test and Applications , 2005 指導老師 : 易序忠 班級 :積體碩一 姓名 :黃順和 學號 :95662009
outline • 1. Introduction • 2. Supply current tests of resistor string DACs • 3. DFT of DACs for current testing • 4. Conclusion
Introduction • In this paper, supply current testability is examined experimentally for opens and shorts in a general 3 bit resistor string Digital/Analog converter(DAC). • we attempted to examine testability of shorts and opens in a DAC in order to check the feasibility of DAC testing based on supply current • we show testability analysis results of current testing in a conventional resistor string DAC. Also, we propose a DFT method of such DACs for supply current testing.
Supply current tests of resistor string DACs • A resistor string DAC is made of a resistor string and MOS switches. Besides them, an operational amplifier and inverter gates are added to the DAC. • In our experiments, a short is inserted between targeted terminals by adding a resistor of 0.1Ω between them in the Spice file of the defect-free circuit. An open is inserted to a targeted terminal by adding a resistor of 10GΩ to the SPICE file.
DFT of DACs for current testing • shorts in DACs will be detected, but opens in MOS switches will not be detected by the current testing • In our design, a transfer gate, an inverter gate and a resistor, Rp, are added to the conventional DAC. In the normal mode, Tst is H. In the test mode, Tst is L and current through Rp is measured.
Conclusion • In order to detect them by current testing, we have proposed a DFT method for register string DACs. It is shown experimentally that all of the opens and shorts will be detected in resistor string DACs designed by using the DFT method. • Exhausted test vector application is required in testsof the testabledesigned DAC. It leads to long test time and some restriction in application of the DFT method.
Defect coverage of DAC • Defect coverage of our testable DAC