A high gain 3-5GHz mixer merged with a very balanced wideband active balun is presented and demonstrated. It uses a Gilbert type folded structure with the active balun as the input trans-conductance stage and with a PMOS switch stage. The implemented circuit in the 0.18um CMOS technology exhibits less than 1dB amplitude imbalance in 2.06-5.2GHz, less than 1.5dB in 0.55-5.7GHz and less than 2 degree phase imbalance through 1.37GHz to 5.07GHz. The mixer exhibits a high IIP3 of -3dBm and a high isolation of LO-RF about -100dB in the wide bandwidth. It consumes only 6.2mW under a 1.8V power supply.

Advance of the fabrication technology has enhanced the size and density for the NAND Flash memory but also brought new types of defects which need to be tested for the quality consideration. This work analyzes three types of physical defects for the deep nano-meter NAND Flash memory based on the circuit level simulation and proposes new categories of interference faults (IFs). Testing algorithm is also proposed to test the faults under the worst case condition. The algorithm, in addition to test IFs, can also detect the conventional address faults, disturbance faults and other RAM-like faults for the NAND Flash.

For very deep sub-micrometer VLSI, crosstalk becomes an important issue in affecting performance and signal integrity of the circuits. Two crosstalk fault effects, namely, glitch and crosstalk-induced delay, in the system-on-chip (SOC) interconnect bus are analyzed and a unified scheme to detect them is proposed and demonstrated in this paper. The crosstalk induced delay is found to be superposition of the induced glitch and the applied signal at the victim line, and this effect is more important in affecting the circuit performance. A pulse detector with an adjustable detection threshold is proposed to detect glitches and consequently the induced delay. Several issues affecting the yield of the proposed testing scheme are discussed and Monte Carlo simulations are conducted to show the feasibility of the scheme.

We propose a multilevel full-chip routing algorithm that improves testability and diagnosability, manufacturability, and signal integrity for yield enhancement. Two major issues are addressed. 1) The oscillation ring test (ORT) and its diagnosis scheme for interconnects based on the popular IEEE Standard 1500 are integrated into the multilevel routing framework to achieve testability enhancement. We augment the traditional multilevel framework of coarsening and uncoarsening by introducing a preprocessing stage that analyzes the interconnect structure for better resource estimation before the coarsening stage, and a final stage after uncoarsening that improves testability to achieve 100% interconnect fault coverage and maximal diagnosability. 2) We present a heuristic to reduce routing congestion to optimize the multiple-fault probability, chemical-mechanical polishing- and optical proximity correction-induced manufacturability, and crosstalk effects, for yield improvement. Experimental results on the Microelectronics Center for North Carolina benchmark circuits show that the proposed ORT method achieves 100% fault coverage and the optimal diagnosis resolution for interconnects. Further, the multilevel routing algorithm effectively balances the routing density to achieve 100% routing completion.

The random-like filling strategy pursuing high compression for today's popular test compression schemes introduces large test power. To achieve high compression in conjunction with reducing test power for multiple-scan-chain designs is even harder and very few works were dedicated to solve this problem. This paper proposes and demonstrates a multilayer data copy (MDC) scheme for test compression as well as test power reduction for multiple-scan-chain designs. The scheme utilizes a decoding buffer, which supports fast loading using previous loaded data, to achieve test data compression and test power reduction at the same time. The scheme can be applied automatic test pattern generation (ATPG)-independently or to be incorporated in an ATPG to generate highly compressible and power efficient test sets. Experiment results on benchmarks show that test sets generated by the scheme had large compression and power saving with only a small area design overhead.

We propose an interconnect diagnosis scheme based on oscillation ring test methodology for SOC design with heterogeneous cores. The target fault models are delay faults and crosstalk glitches. We analyze the diagnosability of an interconnect structure and propose a fast diagnosability checking algorithm and an efficient diagnosis ring generation algorithm which achieves the optimal diagnosability. Two optimization techniques improve the efficiency and effectiveness of interconnect diagnosis. In all experiments, our method achieves 100% fault coverage and the optimal diagnosis resolution.

The random-like filling strategy pursuing high compression for scan test introduces large test power. To pursue high compression in conjunction with reducing test power for multiple scan chain designs is even harder and very few works were dedicated to solve this problem. This paper proposes and demonstrates a multilayer data copy (MDC) scheme for test compression as well as test power reduction for multiple scan designs. The scheme utilizes a buffer, which supports fast load using previous loaded data, to achieve test data compression and test power reduction at the same time. The scheme can be applied ATPG-independently or to be incorporated in an ATPG to generate highly compressible and power efficient test sets. Experiment results on benchmarks show that test sets generated by the scheme had large compression and power saving with little area design overhead

An interconnect diagnosis scheme based on the oscillation ring (OR) test methodology for systems-on-chip (SOC) design with heterogeneous cores is proposed. In addition to traditional stuck-at and open faults, the OR test can also detect and diagnose important interconnect faults such as delay faults and crosstalk glitches. The large number of test rings in the SOC design, however, significantly complicates the interconnect diagnosis problem. In this paper, the diagnosability of an interconnect structure is first analyzed then a fast diagnosability checking algorithm and an efficient diagnosis ring generation algorithm are proposed. It is shown in this paper that the generation algorithm achieves the maximum diagnosability for any interconnect. Two optimization techniques are also proposed, an adaptive and a concurrent diagnosis method, to improve the efficiency and effectiveness of interconnect diagnosis. Experiments on the MCNC benchmark circuits show the effectiveness of the proposed diagnosis algorithms. In all experiments, the method achieves 100% fault detection coverage and the optimal interconnect diagnosis resolution

We propose a novel oscillation ring (OR) test architecture for testing interconnects in SoC. In addition to stuck-at and open faults, this scheme can detect delay faults and crosstalk glitches. IEEE P1500 wrapper cells are modified. An efficient ring-generation algorithm is proposed to construct ORs based on a graph model. Experimental results on MCNC benchmark circuits show the feasibility of the scheme and the effectiveness of the algorithm. Our method achieves 100% fault coverage with a small number of tests.

In this paper, we propose an oscillation-based test methodology for sequential testing. This approach provides many advantages over traditional methods. (1) It is at-speed testing, which makes delay-inducing defects detectable. (2) The ATPG is much easier, and the test set is usually smaller. (3) There is no need to store output responses, which greatly reduces the communication bandwidth between the Automatic Test Equipment (ATE) and Circuit under Test (CUT). We provide a register design that supports the oscillation test, and give an effective algorithm for oscillation test generation. Experimental results on MCNC benchmarks show that the proposed test method achieves high fault coverage with smaller number of test vectors.

For the scan design, the circuit under test (CUT) in the test mode usually has larger switching activity than in the function mode, causing excessive power dissipation. In this paper, we propose a new Scan Matrix (SM) architecture for the scan-based design to achieve low power testing. The scan flip-flops are connected in a matrix style for test and its addressing is controlled by two ring generators during pattern scanning in. Unlike the traditional scan, for which scan-in data need to pass through a long path and many scan flip-flops switch simultaneously, the proposed approach dynamically forms a low-power scan path to reduce test energy and peak power during shift significantly. The architecture is scalable for large designs and has minimal circuit performance penalty. Experimental results show that, for some larger designs, nearly 99% power savings have been achieved.

Scan test for SoC has now suffered large data volume and test application time. In this paper, we propose and demonstrate an Adaptive Encoding scheme to reduce the test volume and test time for SoC scan test. The scheme, instead of handling test data themselves, encodes them in "packets" according to difference bits of two consecutive test patterns. A decoder machine is designed to decode the compressed data and a repeat filling mechanism from the ATE is adopted to eliminate the synchronization problem. It supports variable block size and is flexible in encoding multi-core test patterns; therefore, the proposed method is effective in SoC scan test. Experimental results show that on average the scheme achieves 73% reduction in test data and more than 16 times of speedup in test application time.

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.

The crosstalk fault effects in deep sub-micron VLSI, namely, glitches and the crosstalk-induced delay, are investigated. The origin of their occurrence, relationship and importance in circuit operation are elucidated. It is shown that the crosstalk-induced delay is only superposition of the induced glitch with the original signal delay on the affected victim line; and crosstalk-induced delay is more important in affecting the circuit performance, and should be considered in more details for testing. A scheme which is to detect both types of faults in a unified way by just detecting glitches is proposed and studied, considering the manufacture process variation. In this way, detection of crosstalk-induced faults becomes much easier.

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.

This paper presents a test and diagnosis scheme for feedback type of linear analog circuits with minimal added circuits. For testing, the scheme transforms the circuit-under-test (CUT) into an oscillation circuit by (1) increasing the loop gain of the circuit, and/or (2) reconfiguring the circuit through selectively powering-off operational amplifiers (OP) of the circuit. This eliminates the need of added global paths as in the conventional oscillation test scheme. For diagnosis, the scheme transforms the circuit into a Schmitt trigger type of circuit with a positive-feedback. The output of the circuit under an applied triangular input gives signatures which are used to identify faults. Benchmark circuits have been applied with this scheme and results show that it is very effective for testing and diagnosing the feedback type of linear analog circuit.

A low-power, high-speed, but with a large input dynamic range and output swing class-AB output buffer circuit, which is suitable for flat-panel display application, is proposed. The circuit employs an elegant comparator to sense the transients of the input to turn on charging/discharging transistors, thus draws little current during static, but has an improved driving capability during transients. It is demonstrated in a 0.6 /spl mu/m CMOS technology.

An integrated memory test system is presented. It includes a reconfigurable memory test module, a test algorithm editor, a memory fault simulator, and a test code generator. For a given memory organization, fault list, and test algorithm, the system automatically reports the fault coverage, generates control assembly codes, and produces circuit net list for test pattern generation. The system has been implemented in 9000 lines of C++ program based on the Microsoft Windows graphic user interface. It has been verified on different test algorithms and memory chips.

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.

This paper presents a novel scheme to diagnose single and double faults for linear analog circuits. The scheme first proposes a simple transformation procedure to transform the tested linear analog circuit into a discrete signal flow graph, then constructs "diagnosing evaluators", which model the faulty components, to form a diagnosis configuration to diagnose the faults through digital simulation. This saves much computation time. Furthermore, a simple method to un-power the OP's is also proposed to differentiate equivalent faults. The scheme can diagnose faults in passive components as well as faults in OP's.

In this work, IDDQ current for deep submicron VLSI in year 2011 is estimated with a statistical approach according to the International Technology Roadmap for Semiconductors 1999 Edition considering process variations and different input vectors. The estimated results show that the standard deviation of the IDDQ current is proportional to the square root of the circuit size and the IDDQ currents of the defect-free and the defective devices, which are of the size up to 1/spl times/10/sup 7/ gates, are still differentiable under the condition of random process deviations and input vectors. Two new IDDQ testing schemes, which detect the defective current based on the two separate IDDQ distributions, are proposed. From the study, it is concluded that IDDQ testing is still applicable for the deep submicron VLSI for the next ten years.

This paper proposes an all digital on-chip bus delay and crosstalk measurement methodology. A diagnosis procedure is derived to distinguish the delay faults in drivers, receivers, and wires. The crosstalk profile is plotted by monitoring the changes in delay with the presence of the crosstalk. The distinguished features include all digital design and low hardware overhead. The SPICE simulation results prove the feasibility of the methodology.

In this paper an analog metrology and test stimulus selection guidelines are proposed based on the frequency domain analysis of the stimulus and the CUT. To show the feasibility, a 4th order leapfrog filter and a DSP deconvolution operation are used as the test vehicle. The experimental results on the real measured data show that the increase in observation periods can effectively compensate the increase in the environment noise.

This work proposes an approach to generate weighted random patterns which can maximally excite a circuit during its burn-in testing. The approach is based on a probability model and a maximization procedure to obtain signal transition probability distribution for primary inputs and to generate weighted random patterns according to the obtained probability distribution. It can especially generate weighted random patterns to excite particularly selected "weak nodes" of the circuit in order to expose the early failure of these nodes. Experimental results show that this approach can increase the power dissipation of the total circuit nodes up to 26.68% and the switching activity of particularly selected nodes up to 41.51% respectively.

This paper proposes a method to select flip-flops for partial reset and/or partial scan for sequential circuits to increase their testability. The method gives weights for flip-flops for consideration for partial reset and/or scan based on information on required states for activating faults and the number of faults which propagate to flip-flops, which are obtained during test generation. Since the above information offers the reasons causing the untestable and/or hard-to-detect faults, the method is very efficient in locating flip-flops for partial reset and/or scan to ease test generation task. Experiments showed that this method selected less number of flip-flops for partial reset and scan while produced more testable circuits for benchmark circuits.

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.

In this paper, the optimum functional patterns for CMOS operational amplifier are proposed based on an analysis to find the maximum difference between the good circuit and the faulty circuit for a CMOS operational amplifier. The theoretical and simulation results show that the derived test patterns do give the maximum difference at the output even when the circuit has a "soft" fault. The results have also been applied to generate test patterns for a programmable gain/loss mixed signal circuit.

For sequential circuit test pattern generation incorporating backward justification, we need to justify the values on flip-flops to activate and propagate fault effects. This takes much time when the values to be justified on flip-flops appear to be invalid states. Hence, it is desirable to know invalid states, either dynamically during the justification process or statically before proceeding to test generation. This paper proposes algorithms to identify, before test generation, invalid states for sequential circuits without reset states. The first algorithm explores all valid states from an unknown initial state to search the complete set of invalid states. The second algorithm finds the complete set of invalid states from searching the reachable states for each state. The third algorithm searches the invalid states which are required for test generation to help stop justification early by analyzing dependency among flip-flops to simulate each partial circuit. Experimental results on ISCAS benchmark circuits show that the algorithms can identify invalid states in short time. The obtained invalid states were also used in test generation, and it was shown that they improved test generation significantly in test generation time, fault coverage, and detection efficiency, especially for larger circuits and for those that were difficult to generate.

For sequential circuit test pattern generation, the information on invalid states will help greatly on backward justification to reduce the test generation time. This paper proposes three algorithms to find invalid states for sequential circuit test generation. The first two algorithms search the complete set of invalid states by exploring all valid states and reachable states respectively. The first algorithm is efficient for circuits having more invalid states than valid states while the second algorithm is efficient for circuits having more valid states than invalid states. The third algorithm searches only the invalid states that are required for test generation to stop justification early. Experimental results on ISCAS benchmark circuits show that the algorithm can identify invalid states in short time and can help improve test generation significantly in the fault coverage, detection efficiency, and generation time.

A new multiple-sequence generator scheme to generate a set of deterministic ordered sequence of patterns followed by random patterns is presented in this paper. This scheme is based on an inverted nonlinear autonomous machine which utilizes a two-dimension-like LFSR with nonlinear inverters. A systematic procedure is also presented to obtain the autonomous machine which is more regular in the structure and utilizes less hardware. The generated deterministic sequence of patterns, which may have ordered and repeated patterns, and the random patterns are applicable to sequential circuit testing.

Conventional fault relationships are mostly restricted to faults at a gate or within a fanout free region. In this paper, we analyze the fault relationships beyond the fanout free region for general digital logic circuits. An improved fault collapsing procedure is proposed and applied to several kinds of combinational benchmark circuits and 31 sequential benchmark circuits to collapsing faults. Improvements of 2-8% for an initial set of target faults of a circuit can be obtained. For some of circuits, the reduction ratio can have up to 20% improvement. This may save a lot of time in test generation and fault simulation processes.

In this paper, a programmable multiple-sequence generation scheme, which is constructed from a two-dimension-like feedback shift register structure, to generate a set of deterministic sequence of vectors followed by pseudo-random vectors is presented. A sequence segmentation method is employed to handle a long sequence of vectors. The proposed scheme has a regular structure, and the sequences so generated are more efficient in detecting faults for sequential circuit testing, stuck-open fault testing and delay fault testing. Hence, it is very suitable for the BIST application for MCM testing.

This paper presents a theoretical analysis to identify robust untestable path delay faults. It first classifies the path reconvergence of fanouts into seven cases and deduces the necessary conditions to robustly test path delay faults for each case. It then proposes a procedure, based on the deduced conditions, to identify the robust untestable path delay faults. The procedure was applied to ISCAS 85' circuits and it was found that the robust untestable faults occupy a high percentage of the total path delay faults. In addition, it also presents a method to estimate the number of robust untestable path delay faults for a circuit.

A fast universal test set (UTS) generation algorithm for multi-output functions is presented. The algorithm first generates the UTS for single-output functions by directly Shannon-expanding and complementing the function. This significantly reduces the time complexity and the usage of temporary memory. Also, it stores tests in test cubes to save the size of memory for test storing. Two-six orders of magnitude in computation efficiency improvement and 1-1800 fold for memory saving over the conventional method are achieved. It then merges the generated test cubes for each single-output function into a set of mutually disjoint test cubes to be the UTS for a multi-output function by employing a new compaction technique. The size of UTS thus obtained is 1-20 times smaller than that of UTS without compaction.>

A study is made of single-fault fault collapsing in sequential logic circuits. Two major phenomena, self-hiding (SH) and delayed reconvergence (DR), which arise from the existence of feedback paths and storage elements in sequential circuits, are analyzed and found to cause the dominance relationship which is valid in combinational circuits but no longer valid in sequential circuits. A fault-collapsing procedure is proposed to collapse faults in sequential circuits. It first collapses faults in the non-SAD (self-hiding and delayed-reconvergence) gates of the combinational part of the sequential circuit and then further collapses faults by identifying the prime fan-out branches. Finally, it collapses faults in feedback lines. The collapsed faults constitute a sufficient representative set of prime faults.>

This paper describes a parallel pattern mixed level, i.e. switch-level and gate-level, fault simulator. The switch-level allows the simulator to treat faults at the transistor level while the gate level simulation conserves the simulation speed and the parallel pattern strategy further enhances the simulation speed for more than one order of magnitude.

A study of fault collapsing for synchronous sequential circuits is presented. Two phenomena, self-hiding and delay-reconvergence, which invalidate the combinational fault dominance relationship in sequential circuits are identified. These phenomena are caused by the existence of feedback paths and storage elements in sequential circuits. From this analysis, a single-fault fault-collapsing procedure for synchronous irredundant sequential circuits is proposed to reduce the faults for which test has to be generated. This procedure can be applied not only to a nonscan mode circuit, but also to a full-scan and a partial-scan mode circuit by cutting the inputs and outputs of scannable D flip-flops as the primary outputs and inputs of the circuit, respectively. This procedure has been applied to collapse faults for the 31 benchmark sequential circuits, and a 57% reduction in the number of faults as compared with the total number of original faults has been obtained.>