Design for testability of high-order OTA-C filters

Copyright © 2016 John Wiley & Sons, Ltd.A study of oscillation-based test for high-order Operational Transconductance Amplifier-C (OTA-C) filters is presented. The method is based on partition of a high-order filter into second-order filter functions. The opening Q-loop and adding positive feedback techniques are developed to convert the second-order filter section into a quadrature oscillator. These techniques are based on an open-loop configuration and an additional positive feedback configuration. Implementation of the two testability design methods for nth-order cascade, IFLF and leapfrog (LF) filters is presented, and the area overhead of the modified circuits is also discussed. The performances of the presented techniques are investigated. Fourth-order cascade, inverse follow-the-leader feedback (IFLF) and LF OTA-C filters were designed and simulated for analysis of fault coverage using the adding positive feedback method based on an analogue multiplexer. Simulation results show that the oscillation-based test method using positive feedback provides high fault coverage of around 97%, 96% and 95% for the cascade, IFLF and LF OTA-C filters, respectively. Copyright ÂPeer reviewe

Oscillation-based DFT for Second-order Bandpass OTA-C Filters

This document is the Accepted Manuscript version. Under embargo until 6 September 2018. The final publication is available at Springer via https://doi.org/10.1007/s00034-017-0648-9.This paper describes a design for testability technique for second-order bandpass operational transconductance amplifier and capacitor filters using an oscillation-based test topology. The oscillation-based test structure is a vectorless output test strategy easily extendable to built-in self-test. The proposed methodology converts filter under test into a quadrature oscillator using very simple techniques and measures the output frequency. Using feedback loops with nonlinear block, the filter-to-oscillator conversion techniques easily convert the bandpass OTA-C filter into an oscillator. With a minimum number of extra components, the proposed scheme requires a negligible area overhead. The validity of the proposed method has been verified using comparison between faulty and fault-free simulation results of Tow-Thomas and KHN OTA-C filters. Simulation results in 0.25μm CMOS technology show that the proposed oscillation-based test strategy for OTA-C filters is suitable for catastrophic and parametric faults testing and also effective in detecting single and multiple faults with high fault coverage.Peer reviewedFinal Accepted Versio

Oscillation-based Test Method for Continuous-time OTA-C Filters

“This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder." “Copyright IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.”Design for testability technique using oscillation-based test topology for KHN OTA-C filters is proposed. The oscillation-based test structure is a vectorless output test strategy easily extendable to built-in self-test. During test mode, the filter under test is converted into an oscillator by establishing the oscillation condition in its transfer function. The oscillator frequency can be measured using digital circuitry and deviations from the cut-off frequency indicate the faulty behaviour of the filter. The proposed method is suitable for both catastrophic and parametric fault diagnosis as well as effective in detecting single and multiple faults. The validity of the proposed method has been verified using comparison between faulty and fault-free simulation results of KHN OTA-C filter. Simulation results in 0.25mum CMOS technology show that the proposed oscillation-based test strategy has 84% fault coverage and with a minimum number of extra components, requires a negligible area overhead.Final Published versio

A Multiproject Chip Approach to the Teaching of Analog MOS LSI and VLSI

Multiproject chip implementation has been used in teaching analog MOS circuit design. After having worked with computer simulation and layout aids in homework problems, students designed novel circuits including several high performance op amps, an A/D converter, a switched capacitor filter, a 1 K dynamic RAM, and a variety of less conventional MOS circuits such as a VII converter, an AC/DC converter, an AM radio receiver, a digitally-controlled analog signal processor, and on-chip circuitry for measuring transistor capacitances. These circuits were laid out as part of an NMOS multiproject chip. Several of the designs exhibit a considerable degree of innovation; fabrication pending, computer simulation shows that some may be pushing the state of the art. Several designs are of interest to digital designers; in fact, the course has provided knowledge and technique needed for detailed digital circuit design at the gate level

Analysis of Internally Bandlimited Multistage Cubic-Term Generators for RF Receivers

Adaptive feedforward error cancellation applied to correct distortion arising from third-order nonlinearities in RF receivers requires low-noise low-power reference cubic nonidealities. Multistage cubic-term generators utilizing cascaded nonlinear operations are ideal in this regard, but the frequency response of the interstage circuitry can introduce errors into the cubing operation. In this paper, an overview of the use of cubic-term generators in receivers relative to other applications is presented. An interstage frequency response plan is presented for a receiver cubic-term generator and is shown to function for arbitrary three-signal third-order intermodulation generation. The noise of such circuits is also considered and is shown to depend on the total incoming signal power across a particular frequency band. Finally, the effects of the interstage group delay are quantified in the context of a relevant communication standard requirement

Deployable Payloads with Starbug

We explore the range of wide field multi-object instrument concepts taking advantage of the unique capabilities of the Starbug focal plane positioning concept. Advances to familiar instrument concepts, such as fiber positioners and deployable fiber-fed IFUs, are discussed along with image relays and deployable active sensors. We conceive deployable payloads as components of systems more traditionally regarded as part of telescope systems rather than instruments - such as adaptive optics and ADCs. Also presented are some of the opportunities offered by the truly unique capabilities of Starbug, such as microtracking to apply intra-field distortion correction during the course of an observation.Comment: 12 pages, 8 figures, to be published in Proc. SPIE 6273 "Opto-Mechanical Technologies for Astronomy

Counts and Sizes of Galaxies in the Hubble Deep Field - South: Implications for the Next Generation Space Telescope

Science objectives for the Next Generation Space Telescope (NGST) include a large component of galaxy surveys, both imaging and spectroscopy. The Hubble Deep Field datasets include the deepest observations ever made in the ultraviolet, optical and near infrared, reaching depths comparable to that expected for NGST spectroscopy. We present the source counts, galaxy sizes and isophotal filling factors of the HDF-South images. The observed integrated galaxy counts reach >500 galaxies per square arcminute at AB<30. We extend these counts to faint levels in the infrared using models. The trend previously seen that fainter galaxies are smaller, continues to AB=29 in the high resolution HDF-S STIS image, where galaxies have a typical half-light radius of 0.1 arcseconds. Extensive Monte Carlo simulations show that the small measured sizes are not due to selection effects until >29mag. Using the HDF-S NICMOS image, we show that galaxies are smaller in the near infrared than they are in the optical. We analyze the isophotal filling factor of the HDF-S STIS image, and show that this image is mostly empty sky even at the limits of galaxy detection, a conclusion we expect to hold true for NGST spectroscopy. At the surface brightness limits expected for NGST imaging, however, about a quarter of the sky is occupied by the outer isophotes of AB<30 galaxies. We discuss the implications of these data on several design concepts of the NGST near-infrared spectrograph. We compare the effects of resolution and the confusion limit of various designs, as well as the multiplexing advantages of either multi-object or full-field spectroscopy. We argue that the optimal choice for NGST spectroscopy of high redshift galaxies is a multi-object spectrograph (MOS) with target selection by a micro electro mechanical system (MEMS) device.Comment: 27 pages including 10 figures, accepted for publication in the Astronomical Journal, June 2000, abridged abstrac

Systematic Comparison of HF CMOS Transconductors

Transconductors are commonly used as active elements in high-frequency (HF) filters, amplifiers, mixers, and oscillators. This paper reviews transconductor design by focusing on the V-I kernel that determines the key transconductor properties. Based on bandwidth considerations, simple V-I kernels with few or no internal nodes are preferred. In a systematic way, virtually all simple kernels published in literature are generated. This is done in two steps: 1) basic 3-terminal transconductors are covered and 2) then five different techniques to combine two of them in a composite V-I kernel. In order to compare transconductors in a fair way, a normalized signal-to-noise ratio (NSNR) is defined. The basic V-I kernels and the five classes of composite V-I kernels are then compared, leading to insight in the key mechanisms that affect NSNR. Symbolic equations are derived to estimate NSNR, while simulations with more advanced MOSFET models verify the results. The results show a strong tradeoff between NSNR and transconductance tuning range. Resistively generated MOSFETs render the best NSNR results and are robust for future technology developments