Design of High-Speed Multiplier with Optimised Builtinself-Test

Current trend in Integrated Circuits (IC) implementation such as System-on-Chip has contributed significant advantages in electronic product features such as high circuit performance with high number of functions, small physical area and high reliability. Since the development of System-on-Chip, which is based on integrating subsystems supplied by various Intellectual Properties (IP) Block vendors, the required design time is shorter when compared to that of full-custom IC implementation. However, testing each internal subsystems using the common scan-path method where test data are generated and analyzed externally is considered too time consuming when the number of subsystems is high. Therefore, by including Built-In-Self-Test (BIST) facility into each subsystem is considered a good solution. Commonly, BIST structure is based on random test data generation from a Linear Feedback Shift Register (LFSR) due to its simple, small and economical circuit structure. Since t he number of subsystems in an IC chip is going to be increased from time to time, improvement on the BIST approach is required to provide shorter testing time while keeping the good features of LFSR. For this reason, development of test pattern for BIST based on combination of LFSR and deterministic approach could provide one of the solutions to reduce the testing time. In this research, the possibility of combining LFSR features and deterministic test pattern was carried out. A parallel high-speed multiplier considered as one of the demanding subsystems was chosen to verify the proposed BIST performance. Results show that the testing time (with 100% fault coverage) was reduced significantly when compared to the testing time taken for the BIST that was totally based on random test data generation. One of the reasons for this achievement is only one basic cell of the multiplier is required to determine the test pattern by considering the data flow from one cell to another. Identical test data can then be applied to both multiplier inputs simultaneously. This is the significant finding of the research. Further works based on the finding are also identified

Intermittent Excitation of High-Q Resonators for Low-Power High-Speed Clock Generation

There is growing demand for circuits that can provide ever greater performance from a minimal power budget. Example applications include wireless sensor nodes, mobile devices, and biomedical implants. High speed clock circuits are an integral part of such systems, playing roles such as providing digital processor clocks, or generating wireless carrier signals; this clock generation can often take a large part of a system’s power budget. Common techniques to reduce power consumption generally involve reducing the clock speed, and/or complex designs using a large circuit area. This paper proposes an alternative method of clock generation based on driving a high-Q resonator with a periodic chain of impulses. In this way, power consumption is reduced when compared to traditional resonator based designs; this power reduction comes at the cost of increased period jitter. A circuit was designed and laid out in 0.18µm CMOS, and was simulated in order to test the technique. Simulation results suggest that the circuit can achieve a FoM of 4.89GHz/mW, with a peak period jitter of 10.2ps at 2.015GHz, using a model resonator with a Q-factor of 126

Built-in self-test and self-calibration for analog and mixed signal circuits

Analog-to-digital converters (ADC) are one of the most important components in modern electronic systems. In the mission-critical applications such as automotive, the reliability of the ADC is critical as the ADC impacts the system level performance. Due to the aging effect and environmental changes, the performance of the ADC may degrade and even fail to meet the accuracy requirement over time. Built-in self-test (BIST) and self-calibration are becoming the ultimate solution to achieve lifetime reliability. This dissertation introduces two ADC testing algorithms and two ADC built-in self-test circuit implementations to test the ADC integral nonlinearity (INL) and differential nonlinearity (DNL) on-chip. In the first testing algorithm, the ultrafast stimulus error removal and segmented model identification of linearity errors (USER-SMILE) is developed for ADC built-in self-test, which eliminates the need for precision stimulus and reduces the overall test time. In this algorithm, the ADC is tested twice with a nonlinear ramp, instead of using a linear ramp signal. Therefore, the stimulus can be easily generated on-chip in a low-cost way. For the two ramps, there is a constant voltage shift in between. As the input stimulus linearity is completely relaxed, there is no requirement on the waveform of the input stimulus as long as it covers the ADC input range. In the meantime, the high-resolution ADC linearity is modeled with segmented parameters, which reduces the number of samples required for achieving high-precision test, thus saving the test time. As a result, the USER-SMILE algorithm is able to use less than 1 sample/code nonlinear stimulus to test high resolution ADCs with less than 0.5 least significant bit (LSB) INL estimation error, achieving more than 10-time test time reduction. This algorithm is validated with both board-level implementation and on-chip silicon implementation. The second testing algorithm is proposed to test the INL/DNL for multi-bit-per-stages pipelined ADCs with reduced test time and better test coverage. Due to the redundancy characteristics of multi-bit-per-stages pipelined ADC, the conventional histogram test cannot estimate and calibrate the static linearity accurately. The proposed method models the pipelined ADC nonlinearity as segmented parameters with inter-stage gain errors using the raw codes instead of the final output codes. During the test phase, a pure sine wave is sent to the ADC as the input and the model parameters are estimated from the output data with the system identification method. The modeled errors are then removed from the digital output codes during the calibration phase. A high-speed 12-bit pipelined ADC is tested and calibrated with the proposed method. With only 4000 samples, the 12-bit ADC is accurately tested and calibrated to achieve less than 1 LSB INL. The ADC effective number of bits (ENOB) is improved from 9.7 bits to 10.84 bits and the spurious-free dynamic range (SFDR) is improved by more than 20dB after calibration. In the first circuit implementation, a low-cost on-chip built-in self-test solution is developed using an R2R digital-to-analog converter (DAC) structure as the signal generator and the voltage shift generator for ADC linearity test. The proposed DAC is a subradix-2 R2R DAC with a constant voltage shift generation capability. The subradix-2 architecture avoids positive voltage gaps caused by mismatches, which relaxes the DAC matching requirements and reduces the design area. The R2R DAC based BIST circuit is fabricated in TSMC 40nm technology with a small area of 0.02mm^2. Measurement results show that the BIST circuit is capable of testing a 15-bit ADC INL accurately with less than 0.5 LSB INL estimation error. In the second circuit implementation, a complete SAR ADC built-in self-test solution using the USER-SMILE is developed and implemented in a 28nm automotive microcontroller. A low-cost 12-bit resistive DAC with less than 12-bit linearity is used as the signal generator to test and calibrate a SAR ADC with a target linearity of 12 bits. The voltage shift generation is created inside the ADC with capacitor switching. The entire algorithm processing unit for USER-SMILE algorithm is also implemented on chip. The final testing results are saved in the memory for further digital calibration. Both the total harmonic distortion (THD) and the SFDR are improved by 20dB after calibration, achieving -84.5dB and 86.5dB respectively. More than 700 parts are tested to verify the robustness of the BIST solution

Bridging the Testing Speed Gap: Design for Delay Testability

The economic testing of high-speed digital ICs is becoming increasingly problematic. Even advanced, expensive testers are not always capable of testing these ICs because of their high-speed limitations. This paper focuses on a design for delay testability technique such that high-speed ICs can be tested using inexpensive, low-speed ATE. Also extensions for possible full BIST of delay faults are addresse

Discrete-Time Chaotic-Map Truly Random Number Generators: Design, Implementation, and Variability Analysis of the Zigzag Map

In this paper, we introduce a novel discrete chaotic map named zigzag map that demonstrates excellent chaotic behaviors and can be utilized in Truly Random Number Generators (TRNGs). We comprehensively investigate the map and explore its critical chaotic characteristics and parameters. We further present two circuit implementations for the zigzag map based on the switched current technique as well as the current-mode affine interpolation of the breakpoints. In practice, implementation variations can deteriorate the quality of the output sequence as a result of variation of the chaotic map parameters. In order to quantify the impact of variations on the map performance, we model the variations using a combination of theoretical analysis and Monte-Carlo simulations on the circuits. We demonstrate that even in the presence of the map variations, a TRNG based on the zigzag map passes all of the NIST 800-22 statistical randomness tests using simple post processing of the output data.Comment: To appear in Analog Integrated Circuits and Signal Processing (ALOG

A low-speed BIST framework for high-performance circuit testing

Testing of high performance integrated circuits is becoming increasingly a challenging task owing to high clock frequencies. Often testers are not able to test such devices due to their limited high frequency capabilities. In this article we outline a design-for-test methodology such that high performance devices can be tested on relatively low performance testers. In addition, a BIST framework is discussed based on this methodology. Various implementation aspects of this technique are also addresse

Analysis and application of digital spectral warping in analog and mixed-signal testing

Spectral warping is a digital signal processing transform which shifts the frequencies contained within a signal along the frequency axis. The Fourier transform coefficients of a warped signal correspond to frequency-domain 'samples' of the original signal which are unevenly spaced along the frequency axis. This property allows the technique to be efficiently used for DSP-based analog and mixed-signal testing. The analysis and application of spectral warping for test signal generation, response analysis, filter design, frequency response evaluation, etc. are discussed in this paper along with examples of the software and hardware implementation