DESIGN FOR IDDQ TESTABILITY PDF

Then one has to compare the costs of both kinds of erroneous decisions: For example, in [ This shall be demonstrated for the e xample of a hard combinatorial bridgin g fault section It may also be used to improve the r eliabilit y of chips section But since such a resistor within a supply line will reduce the applied voltage it has to be shorted by a transistor for normal operation of the chip. As an alternative approach the resistor can be re- placed by a capacitor. I am very confused. Of course faults can also cause an increased current during the phase transient states.

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Nikoran The Concept of Electronic Design Automation: Further faults that cause an increase of quiescent current are bridgin g faultsand gat e oxide shorts. Multipl e faults do not cause additional problems for IDDQ testing. PV charger battery circuit 4. If it extends a certain threshold value the chip fails the IDDQ test. But this may not be true for an interruption of a wire. Of course faults can also cause an increased current during the phase transient states.

In order to apply an IDDQ test the circuit has to satisfy special properties. Leave a comment Cancel reply Your email address will not be published. An increased current can even be caused by a transistor stu c k open fault.

This way it is possible to perform an IDDQ test without hardware overhead. As an alternative approach the resistor can be re- placed by a capacitor. On the other hand, such simulations can also be used to determine the accuracy needed for an IDDQ measurement. Thus the IDDQ method cannot replace functional tests but can extend such tests to improve defect coverage.

ModelSim — How to force a struct type written in SystemVerilog? I mean from top module itself? Synthesized tuning, Part 2: IDDQ test pattern generation also has to calculate the intensity of quiescent current.

Functional Undetectable Defects With functiona l tests one tries to stimulate a fault and to propagate resulting erroneous signals to a primary output. Again, for normal operation it is shorted and unloaded. Input port and input output port declaration in top module 2. Therefore on using the IDD Q test it is possible to detect defects that can not yet be detected by functional tests.

What are the expected costs if a defect chip remains undetected and what does is cost to classify a correct chip as faulty? In which case i compulsory need to use Iddq testing and not stuck-at fault test.? I am not getting desigm picture.

So the consider fault is undetectable. PNP transistor not working 2. I hope you got it. The stop point indicated by the tool is when you should measure the current. This effect is called fault masking, where one fault in the circuit testabilitt mask the other fault. Design for Testability:IDDQ Test pcb design And while applying test pattern for any one fault will give the expected output and not the faulty output.

Turn on power triac — proposed circuit analysis 0. How do you get an MCU design to market quickly? Built In Current Sensor [ For example, in [ For testing, the transistor is opened and the capacitor is loaded by the quiescent current. Your email address will not be published. Dec Such an increase of current might be owed to a physical defect of the chip.

Here the n-transistor is well suited to transmit the value 0 and the p- transistor testavility well suited to transmit 1. Back-end Design Tools Physical Design: It is also possible that despite the fault the voltage at the output y may be interpreted as the correct logic value. Here we will conclude that their is no pattern gor can detect both the fault at a time. Nevertheless, it is conceivable that despite the defect the functional behavior of the chip is correct.

For this task a method is described in [ Depending on the resistance of transistor channels, the value of the output signal y results from the voltage divider built by T 1 and T 2.

To discover such effects one uses IDD T tests, observing t r ansient cur r en t. Choosing IC with EN signal 2. Related Posts.

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Design for testing

Nikoran The Concept of Electronic Design Automation: Further faults that cause an increase of quiescent current are bridgin g faultsand gat e oxide shorts. Multipl e faults do not cause additional problems for IDDQ testing. PV charger battery circuit 4. If it extends a certain threshold value the chip fails the IDDQ test. But this may not be true for an interruption of a wire. Of course faults can also cause an increased current during the phase transient states.

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DESIGN FOR IDDQ TESTABILITY PDF

Taujind Nevertheless, it is conceivable that despite the defect the functional behavior of the chip is correct. Also pul l up resistors have to be disabled for the test fo, and for pa d drivers, analog cells, and bipolar sub- circuits a separate power supply is needed because they typically have a high power consumption. I hope you got it. To discover such effects one testabllity IDD T tests, observing t r ansient cur r en t.

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The design modifications can be strictly physical in nature e. While controllability and observability improvements for internal circuit elements definitely are important for test, they are not the only type of DFT. Other guidelines, for example, deal with the electromechanical characteristics of the interface between the product under test and the test equipment. Examples are guidelines for the size, shape, and spacing of probe points, or the suggestion to add a high-impedance state to drivers attached to probed nets such that the risk of damage from back-driving is mitigated. The common understanding of DFT in the context of Electronic Design Automation EDA for modern microelectronics is shaped to a large extent by the capabilities of commercial DFT software tools as well as by the expertise and experience of a professional community of DFT engineers researching, developing, and using such tools.

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