Jwu E. Chen

Oscillation Ring Delay Test for High Performance Microprocessors

This paper proposes a new test scheme, oscillation ring test, and its associated test circuit organization for delay fault testing for high performance microprocessors. For this test scheme, the outputs of the circuit under test are connected to its inputs to form oscillation rings and test vectors which sensitize circuit paths are sought to make the rings oscillate. High speed transition counters or oscillation detectors can then be used to detect whether the circuit is working normally or not. The sensitizable paths of oscillation rings cover all circuit lines, detecting all gate delay faults, a large part of hazard free robust path delay faults and all the stuck-at faults. It has the advantage of testing the circuit at the working speed of the circuit. Also, with some modification, the scheme can also be used to measure the maximum speed of the circuit. The scheme needs minimal simple added hardware, thus ideal for testing, embedded circuits and microprocessors.

Structural Fault Based Specification Reduction for Testing Analog Circuits

Specification reduction can reduce test time, consequently, test cost. In this paper, a methodology to reduce specifications during specification testing for analog circuit is proposed and demonstrated. It starts with first deriving relationships between specifications and parameter variations of the circuit-under-test (CUT) and then reduces specifications by considering bounds of parameter variations. A statistical approach by taking into account of circuit fabrication process fluctuation is also employed and the result shows that the specification reduction depends on the testing confidence. A continuous-time state-variable benchmark filter circuit is applied with this methodology to demonstrate the effectiveness of the approach.

A new BIST scheme based on a summing-into-timing-signal principle with self calibration for the DAC

In this paper, we propose a BIST scheme for the digital-to-analog converter (DAC). For the scheme, an analog summer is employed and the tested signal is transformed into a timing signal for a more precise measurement. Also, a calibration circuit is added to calibrate analog imperfection to increase accuracy of the BIST circuit. An 8-bit DAC BIST circuit is designed for demonstration.

A testing scheme for crosstalk faults based on the oscillation test signal [VLSI]

A test scheme for crosstalk faults, based on an oscillation signal, is proposed. It uses an oscillation signal applied to an affecting line and detects induced pulses on a victim line if a crosstalk fault exists between these two lines. It is simple and eliminates the complicated timing issues during test generation for crosstalk faults in conventional approaches. The test generation and fault simulation based on the scheme are described. Experimental results are also presented to show the described test generation procedure is effective in generating test patterns for this scheme.

A DFT for semi-DC fault diagnosis for switched-capacitor circuits

In this paper, a design-for testability (DFT) technique is presented to diagnose switched-capacitor (SC) circuits. In order to avoid the effect that pure DC signals cannot pass through unswitched capacitors, we use a semi-DC signal to diagnose SC circuits. Furthermore, we propose a controllable op amp that can be controlled to normal mode or test mode. In normal mode, it passes the signal normally; in test mode, it provides a semi-DC test signal (VDD or VSS) and blocks the signals from the stage before controlled stage. In our diagnosis method, we consider faults both in capacitors and in op amps. Experiments have been carried out to verify the practicality of this technique.

A methodology for fault model development for hierarchical linear systems

In this paper, a methodology to develop fault models for hierarchical linear systems which are composed of operational amplifiers (OP) is demonstrated and presented. The methodology at first presents a transfer function model for the open-loop OP based on analysis of element faults at the transistor level. Then it derives a transfer function model for the closed loop OP based on the derived open-loop OP level model, again a higher level fault model for a module which is composed of closed loop OPs. The models can handle ac faults. The benchmark state-variable filter is used as an example to demonstrate for this methodology. An application of the derived models to Monte Carlo simulation to save computation time is also demonstrated.

Structure-Based Specification-Constrained Test Frequency Generation for Linear Analog Circuits

In this paper, an approach to generating the sinusoidal stimulus of the right frequency of a linear analog circuit for testing circuit parameter faults under the constraints of the specifications of the circuit under test (CUT) is presented. This approach considers tolerance bounds due to fabrication process fluctuations of tested parameters using a statistical model and maps them to an accepted region of the observed signature of the CUT. The generated test stimulus is derived based on a proposed testing confidence level. Test generation procedures for both the monotonic and non-monotonic relationships between the signature and the parameter are proposed and demonstrated. The procedures are applied to a continuous time state-variable filter example circuit to show the effectiveness of the methodology.

Complete test set for multiple-valued logic networks

A complete test set (CTS) is defined and derived for multiple-valued logic (MVL) Min/Max networks. The CTS can detect any single and multiple stuck-at faults of the MVL Min/Max network regardless of its implementation. Two splitting algorithms to generate the CTS or a given MVL function are proposed. One algorithm demonstrates over 2 orders speed improvement and 3 orders memory savings and the other algorithm demonstrates over 4 orders speed improvement and 2 orders memory savings with respect to the conventional truth table enumerating method.<<ETX>>

A two-phase fault simulation scheme for sequential circuits

A two-phase fault simulation scheme for sequential circuits is proposed. In this fault simulation, the input sequence is divided into two parts. In the first phase, fault free simulation is performed with the first sequence of patterns. In the second phase, fault simulation is performed with the rest of the patterns. Five cases of faults which result from two-phase fault simulation are discussed in detail. Significant speedup in simulation time can be obtained because this fault simulation approach can quickly drop Case 1 faults, which are time-consuming faults and would be considered undetectable in the traditional three-value fault simulation but are actually detected in exact fault simulation. Almost ”exact” results can be obtained for detected faults except for a small percentage of over-detected-faults (ODFs) and under-detected-faults (UDFs).

Fault diagnosis of odd-even sorting networks

This paper investigates detection and location for single faults in odd-even sorting networks. In the work, we have found that three tests are enough to locate single link fault and four tests are sufficient to detect single sorting element fault in an odd-even sorting network. For location tests for sorting element faults, the numbers of tests depend on the type of faults occurring at the sorting element. For most types of sorting element faults, the numbers are less than four specific tests. For the other types of faults, we have presented the test generation procedure and binary search procedures to generate the tests. The numbers of location tests are less than (n+log/sub 2/n), where n=log/sub 2/N and N is the number of inputs of the sorting network.