Highly testable design of BiCMOS logic circuits

Most of the work reported in the literature to date on the testability of BiCMOS circuits has concentrated on fault characterization and the need for a suitable testing method that can address the peculiarities of BiCMOS circuits. The problem of adequately testing large BiCMOS logic networks remains open and complex. In this paper, we introduce a new design for testability technique for BiCMOS logic gates that results in highly testable BiCMOS logic circuits. The proposed design incorporates two features: a test charge/discharge path and built-in current sensing (BICS). The test charge/discharge path is activated only during testing and facilitates the testing of stuck-open faults using single test vectors. BICS facilitates testing of faults that cause excessive IDDQ. HSPICE simulation results show that the proposed design can detect stuck-open faults at a test speed of 10 MHz. Faults causing excessive IDDQ are detected by BICS with a detection time of 1 ns and a settling time of 2 ns. Impact of the proposed design on normal operation is minimal. The increase in propagation delay in normal operation is less than 3%. This compares very favorably with CMOS BICS reported in the literature, where the propagation delay increase was 20%, 14.4% respectively. The increase in the area is less than 15%     

Fault characterization, testing considerations, and design fortestability of BiCMOS logic circuits

The results of a simulation-based fault characterization study of BiCMOS logic circuits are given. Based on the fault characterization results, the authors have studied different techniques for testing BiCMOS logic circuits. The effectiveness of stuck-at fault testing, stuck-open fault testing, delay fault testing, and current testing in achieving a high level of defect coverage is studied. A novel BiCMOS circuit structure that improves the testability of BiCMOS digital circuits is presented     

Active-pull-down nonthreshold logic BiCMOS circuits for high-speedlow-power applications

A new active-pull-down nonthreshold logic (APD-NTL) BiCMOS circuit is presented and its performance has been evaluated and compared to that of standard NTL gate. The circuit utilizes an NMOS active-pull-down emitter-follower stage. A first-order analysis has been conducted to demonstrate the NMOS-APD concept. Simulation results based on 0.6 μm BiCMOS technology indicate that at a power consumption of 1 mW/gate, the APD-NTL circuit offers 4× improvement in the load driving capability and 3.4× improvement in the speed compared to conventional NTL circuits for a load of 1 pF/gate and a logic swing of 800 mV     

Full-swing BiCMOS logic circuits with complementaryemitter-follower driver configuration

Various full-swing BiCMOS logic circuits with complementary emitter-follower driver configurations are described. The performance of the circuits is demonstrated in a 1.2 μm complementary BiCMOS technology with a 6 GHz n-p-n and a 2 GHz p-n-p transistor. For the basic circuit, gate delay (fan-in=2, fan-out=1) is 366 ps and driving capability is 288 ps/pF at 4 V. Delay-power tradeoffs that depend on characteristics of the clamping diode between two base nodes of the complementary emitter-follower driver, parasitic capacitances at the two base nodes, and a technique that can be used to achieve full swing have been identified for these circuits. These circuits show leverage over the conventional BiCMOS circuit for reduced power-supply voltages     

Testability analysis and fault modeling of BiCMOS circuits

Defect models have been used for testability analysis of BiCMOS circuits and the results have been compared with an analysis of CMOS circuits. Using a nominal point approach, faults generated are classified as logical or performance degradation faults. It is found that logical fault testing can only cover a small percentage of the total fault set, 54% for BiCMOS, versus 69% for equivalent CMOS gates. Delay faults and current faults are analyzed as applied to BiCMOS and CMOS gates. It is shown that logical fault testing in conjunction with either delay fault testing or current fault testing promises the highest fault coverage for BiCMOS logic gates, around 95%.This research was partially supported by the Department of National Defence of Canada, Academic Research Program, grant # 3705-921.     

3.3-V BiCMOS current-mode logic circuits for high-speed adders

New high-speed BiCMOS current mode logic (BCML) circuits for fast carry propagation and generation are described. These circuits are suitable for reduced supply voltage of 3.3-V. A 32-b BiCMOS carry select adder (CSA) is designed using 0.5-μm BiCMOS technology. The BCML circuits are used for the correct carry path for high-speed operation while the rest of the adder is implemented in CMOS to achieve high density and low power dissipation. Simulation results show that the BiCMOS CSA outperforms emitter coupled logic (ECL) and CMOS adders     

Testable design of BiCMOS circuits for stuck-open fault detectionusing single patterns

Single BJT BiCMOS devices exhibit sequential behavior under transistor stuck-OPEN (s-OPEN) faults. In addition to the sequential behavior, delay faults are also present. Detection of s-OPEN faults exhibiting sequential behavior needs two-pattern or multipattern sequences, and delay faults are all the more difficult to detect. A new design for testability scheme is presented that uses only two extra transistors to improve the circuit testability regardless of timing skews/delays, glitches, or charge sharing among internal nodes. With this design, only a single vector is required to test for a fault instead of the two-pattern or multipattern sequences. The testable design scheme presented also avoids the requirement of generating tests for delay faults     

BiCMOS logic testing

With the anticipated growth of BiCMOS technology for high-performance ASIC design, the issue of testing takes on great significance. This paper addresses the testing of BiCMOS logic circuits. Since many different implementations of BiCMOS gates have been proposed, four representative ones are studied. The adequacy of stuck-at, quiescent current, and delay testing are examined based on circuit level faults. It is demonstrated that a large portion of the defects cannot be detected by common stuck-at or quiescent current tests since they manifest themselves as delay faults. By using the results presented, the test methodologies and the logic families can be ranked based on fault coverage. This ranking can then be used to help decide which BiCMOS solution is proper for a given application     

Differential fault simulation for sequential circuits

A new fast fault simulation algorithm called differential fault simulation, DSIM, for synchronous sequential circuits is described. Unlike concurrent fault simulation, for every test vector, DSIM simulates the good machine and each faulty machine separately, one after another, rather than simultaneously simulating all machines. Therefore, DSIM dramatically reduces the memory requirement and the overhead in the memory management in concurrent fault simulation. Also, unlike serial fault simulation, DSIM simulates each machine by reprocessing its differences from the previously simulated machine. In this manner, DSIM is more efficient than serial fault simulation. Experiments have shown that DSIM runs 3 to 12 times faster than an existing concurrent fault simulator. In addition, owing to the simplicity of this algorithm, DSIM is very easy to implement and maintain. An implementation consists of only about 300 lines of C language statements added to the event-driven true-value simulator in an existing sequential circuit test generator program, STG3. Currently DSIM uses the zero-delay timing model. The addition of alternative delay models is under development.     

A BiCMOS wired-OR logic

This paper proposes a BiCMOS wired-OR logic for high-speed multiple input logic gates. The logic utilizes the bipolar wired-OR to circumvent the use of a series connection of MOS transistors. The BiCMOS wired-OR logic was found to be the fastest compared with such conventional gates as CMOS NOR, BiCMOS multiemitter logic and CMOS wired-NOR logic, when the number of inputs was more than four and the supply voltage was 3.3 V. The BiCMOS wired-OR logic was also determined to be the fastest of the four when the fan-out number was below 20 and the number of inputs was eight. In addition, the speed was more than twice as faster when the fan-out number was less than 10. The BiCMOS wired-OR logic was applied to a 64-b 2-stage carry look-ahead adder, and was fabricated with a 0.5-μm BiCMOS process technology. A critical path delay time of 3.1 ns from an input to a sum output was obtained at the supply voltage of 3.3 V. This is 35% faster than that of conventional BiCMOS adders     

Bootstrapped full-swing BiCMOS/BiNMOS logic circuits for 1.2-3.3 Vsupply voltage regime

Novel full-swing BiCMOS/BiNMOS logic circuits using bootstrapping in the pull-up section for low supply voltage down to 1 V are reported. These circuit configurations use noncomplementary BiCMOS technology. Simulations have shown that they outperform other BiCMOS circuits at low supply voltage using 0.35 μm BiCMOS process. The delay and power dissipation of several NAND configurations have been compared. The new circuits offer delay reduction between 40 and 66% over CMOS in the range 1.2-3.3 V supply voltage. The minimum fanout at which the new circuits outperform CMOS gate is 5, which is lower than that of other gates particularly for sub-2.5 V operation     

BiCMOS tunable membership function circuits

An MOS transconductance amplifier and bipolar current gain cell structure were investigated. The large input voltage range of the MOS transconductance is preserved, while the gain in the bipolar cell is linearly current controlled. These features make the structure suitable for tunable membership function circuits (MFCs) in a fuzzy controller. Both current-output and voltage-output configurations are proposed.     

Scaling of digital BiCMOS circuits

A generalized first-order scaling theory for BiCMOS digital circuit structures is presented. The effect of horizontal, vertical, and voltage scaling on the speed performance of various BiCMOS circuits is presented. The generalized scaling theory is used for the MOSFET, and the constant collector current (CIC) scaling scheme is used for the bipolar junction transistor (BJT). In scaling the bipolar transistor, polysilicon emitter contact and bandgap narrowing are taken into account. A case study for scaling BiCMOS circuits operating at 5- and 3.3-V power supplies shows that scaling improved BiCMOS buffers more significantly than CMOS buffers. Moreover, the low delay-to-load sensitivity of BiCMOS is preserved with scaling     

A new fault independent test generation algorithm for combinational logic circuits

In order to improve the performance of fault independent test generation algorithms, two strategies are proposed: a critical lines maximization strategy (CLM) and a critical primary inputs flipping strategy (CPF). CLM is used to maximize the number of detected faults while generating a test pattern. CPF is used to derive new test pattern(s) from a generated test pattern with little additional effort. A new fault independent test generation algorithm (MAX) based on these strategies is introduced and illustrated.     

Novel low-voltage low-power full-swing BiCMOS circuits

A novel BiCMOS full-swing circuit technique with superior performance over CMOS down to 1.5 V is proposed. A conventional noncomplementary BiCMOS process is used. The proposed pull-up configuration is based on a capacitively coupled feedback circuit. Several pull-down options were examined and compared, and the results are reported. Several cells were implemented using the novel circuit technique; simple buffers, logic gates, and master-slave latches. Their performance, regarding speed, area, and power, was compared to that of CMOS for different technologies and supply voltages. Both device and circuit simulations were used. A design procedure for the feedback circuit and the effects of scaling on that procedure were studied and reported     

Low-voltage, low-power BiCMOS digital circuits

A new BiCMOS buffer circuit, for low-voltage, low-power environment, is presented. The circuit is based on the deep submicron technology and utilizes the parasitic bipolar transistors associated with the CMOS structure. The analysis, simulations and SPICE results confirm the functionality of the circuit and its speed and voltage swing superiority, compared with conventional BiCMOS circuits at low supply voltages     

BiCMOS logic circuit for single-battery operation

A novel BiCMOS logic circuit is described that provides highspeed rail-to-rail operation with only one battery cell (1-1.5 V). The proposed circuit utilises a novel pull-down scheme that involves bootstrapping the base of the pull-down p-n-p bipolar junction transistor to a negative potential during the pull-down transient period. Circuit simulations have shown that the proposed circuit outperforms the transient-saturation full-swing BiCMOS and the bootstrapped bipolar circuits in terms of delay, power and cross-over capacitance for all simulated supply voltages     

量子逻辑电路故障检测定位及自修复方法研究

针对量子逻辑电路规模逐渐增大,电路可靠性逐渐下降的问题,提出基于单个量子逻辑门在线故障检测定位方法,该方法使用新构造的检测信号生成门与故障检测门,利用奇偶保持特性判断待测量子逻辑门是否发生故障,同时在设计过程中对信号检测电路进行检验,保证检测电路的正确性。此外提出了基于硬件冗余的量子逻辑电路自修复设计方法。实验结果表明,文中故障检测方法在量子门和垃圾位等性能指标上相对已有方法均有了改进,首次实现的量子逻辑电路的自修复设计大大提高了电路的容错能力和可靠性。     

Self-timed logic circuits

Self-timed and asynchronous design techniques are currently proposed as a vehicle for pushing digital integrated circuits to higher levels of density and performance. The arguments for and against the adoption of these techniques are presented with illustrations from practical development projects. Some of the key principles behind self-timed operation are reviewed. Design tools to enable complex practical applications to be engineered are considered. For engineers who wish to find out more a selection of key references is provided     

Digital logic circuits

Recent progress in Josephson digital logic circuits is described. It is noted that changing the junction material from a lead alloy to niobium has dramatically improved process reliability, and that high-speed, low-power operations have been demonstrated at large-scale integrated-circuit levels. The first Josephson microprocessor, operated at 770 MHz, verified the potential of Josephson devices for future digital elements. The possibilities of the ultrafast Josephson computer, previously shelved because of a number of problems, are being actively reconsidered. The performance anticipated for Josephson digital circuits using high-temperature superconducting materials is also discussed