H.M.D. Ip

Imperial College London, Londinium, England, United Kingdom

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Publications (9)4.61 Total impact

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    ABSTRACT: This paper presents proof-of-concept measured results from CMOS hyperbolic-sine (sinh) filters fabricated in a commercially available 0.35 µm CMOS technology. Results from two chips are reported: a practical sinh integrator and a high order (8th) notch filter dedicated to 50/60 Hz noise rejection and synthesized by means of the proposed integrator. Linearity, frequency and noise measurements are reported. The notch frequency of the 8th order filter can be tuned over almost two decades. Its attenuation exceeds 70 dB for the target frequency range of 20–60 Hz and its dynamic range (for THD<4%) amounts to 89 dB while consuming 8 µW from a 2 V power supply level. For an increased power consumption of 74 µW its dynamic range (for THD<4%) exceeds 100 dB.
    Microelectronics Journal 12/2013; 44(12):1268–1277. · 0.92 Impact Factor
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    ABSTRACT: SUMMARY This paper advances the field of externally linear–internally nonlinear (ELIN) filters by introducing a synthesis method that enables the design of high-order class-AB sinh filters by means of complementary metal–oxide semiconductor (CMOS) weak-inversion sinh integrators comprising only one type of devices in their translinear loops. The proposed transistor-level synthesis approach is demonstrated through the examples of (1) a biquadratic and (2) a fifth-order filter, and their simulated performance is studied. The biquadratic filter achieves a dynamic range of 94 dB and has a tunable quality factor Q up to the value of 8, whereas its natural frequency can be tuned for four orders of magnitude. Its static power consumption amounts to 6.2 μW for Q = 1 and fo = 2 kHz. The fifth-order Chebyshev sinh CMOS filter with a cut-off frequency of 100 Hz, a pass band ripple of 1 dB, and a power consumption of ~300 nW is compared head-to-head with its pseudo-differential class-AB CMOS log domain counterpart. The sinh filter achieves similar or better signal-to-noise ratio (SNR) and signal-to-noise-plus-distortion ratio (SNDR) performances with half the capacitor area but at the expense of higher power consumption from the same power supply level. All three presented filter topologies are novel. Cadence design framework simulations have been performed using the commercially available 0.35 µm AMS (austriamicrosystems) process parameters. Copyright © 2013 John Wiley & Sons, Ltd.
    International Journal of Circuit Theory and Applications 04/2013; · 1.29 Impact Factor
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    ABSTRACT: This work falls into the category of linear cellular neural network (CNN) implementations. We detail the first investigative attempt on the CMOS analog VLSI implementation of a recently proposed network formalism, which introduces time-derivative ‘diffusion’ between CNN cells for nonseparable spatiotemporal filtering applications—the temporal-derivative CNNs (TDCNNs). The reported circuit consists of an array of Gm-C filters arranged in a regular pattern across space. We show that the state–space coupling between the Gm-C-based array elements realizes stable and linear first-order (temporal) TDCNN dynamics. The implementation is based on linearized operational transconductance amplifiers and Class-AB current mirrors. Measured results from the investigative prototype chip that confirms the stability and linearity of the realized TDCNN are provided. The prototype chip has been built in the AMS 0.35 µm CMOS technology and occupies a total area of 12.6 mm sq, while consuming 1.2 µW per processing cell. Copyright © 2010 John Wiley & Sons, Ltd.
    International Journal of Circuit Theory and Applications 10/2010; 39(6):665 - 678. · 1.29 Impact Factor
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    ABSTRACT: Recently, the authors have proposed a network formalism (TDCNNs) which introduces Time-Derivative coupling between linearized-CNN cells (with output nonlinearity removed) and demonstrated its use in realizing non-separable 3D spatiotemporal filters. TDCNNs assume inputs in the form of time-varying 2D array of pixels and processing is carried out in continuous-time. Due to this continuous-time nature of TDCNNs, it can be conveniently implemented with an array of continuous-time filters, each coupled to its nearest neighbors according to the feedforward/feedback and temporal-derivative templates. Analog circuit building blocks and simulation results from our first attempt in implementing TDCNNs with full custom CMOS was presented previously. This paper follows from our previous presentation and includes some of the measured results obtained from the fabricated prototype with 5 �? 5 two-layered cells.
    01/2010;
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    ABSTRACT: This paper contributes to the field of low-power high-order CMOS log-domain filters by: (a) suggesting a log-domain synthesis path which bypasses the need for E-minus cells and (b) by assessing the practicality of the proposed synthesis path by means of a 6th-order CMOS log-domain Bessel filter fabricated in the commercially available AMS 0.35μm process. Measured results from the 19nW, 8–200Hz, 940μm2 Bessel filter chip confirm the validity of the proposed approach. The filter reported here is particularly useful for biomedical instruments such as portable ECG devices and Pulse-oximeters.
    Microelectronics Journal 08/2009; 40:1170-1174. · 0.92 Impact Factor
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    ABSTRACT: Using a modified version of the linear cellular neural network (CNN) filtering paradigm recently proposed by the authors, we designed a nonseparable spatiotemporal bandpass filter with tunable spatiotemporal passband volumes. The filter presented here qualitatively resembles spatiotemporal receptive field models for the primary visual cortex. Numerical simulation results confirm the bandpass characteristic of our filtering network.
    Circuits and Systems, 2008. ISCAS 2008. IEEE International Symposium on; 06/2008
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    ABSTRACT: Linear cellular neural networks (CNNs) are capable of performing efficient spatiotemporal filtering operations as recursive infinite impulse response (IIR) filters. Particularly, linear CNNs can be characterized as a spatial frequency-dependent recursive temporal filter with complex coefficients. Based on a modified version of the CNN paradigm recently proposed by the authors, nonseparable spatiotemporal bandpass filters with tunable spatiotemporal passband volumes are synthesized. The filters reported here qualitatively resemble spatiotemporal receptive field models for the primary visual cortex. Numerical simulation results confirm the bandpass characteristics of our filtering network.
    Circuits and Systems I: Regular Papers, IEEE Transactions on 03/2008; · 2.30 Impact Factor
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    ABSTRACT: In this paper, we extend the linear cellular neural network (CNN) paradigm by introducing temporal derivative diffusion connections between neighboring cells. Our proposal results in an analog network topology for implementing general continuous-time discrete-space mixed-domain 3-D rational transfer functions for linear filtering. The network connections correspond one-to-one to the transfer function coefficients. The mixed-domain frequency response is treated as a temporal frequency-dependent spatial function and we show how nonseparable properties of the spatio-temporal magnitude response can be derived from the combination of: 1) sinusoidal functions of spatial frequencies and 2) polynomials of the continuous-time frequency in the 3-D frequency response expression. A generic VLSI-compatible implementation of the network based on continuous-time integrators is also proposed. Based on our proposed CNN extension, the analysis of a spatio-temporal filtering example originated from analytical modeling of receptive fields of the visual cortex is presented and a spatio-temporal cone filter is designed and presented with numerical simulation results.
    Circuits and Systems I: Regular Papers, IEEE Transactions on 03/2008; · 2.30 Impact Factor
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    IEEE Trans. on Circuits and Systems. 01/2008; 55-I:298-310.
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    ABSTRACT: This paper outlines the design and simulated performance of a novel, current-mode, companding, Class-AB, Sinh lossy integrator. Prior Sinh filter designs utilize current conveyor-like blocks which incorporate both N- and P-type devices in alternate cascode arrangement to process the split-ted phases of the input. However, if these blocks were to be designed in weak inversion CMOS, the bulks of all the devices involved should be connected to their respective sources for accurate exponential/logarithmic conformity, which dictates the use of a triple-well process. Triple-well processes, apart from the fact that are not always available, have increased parasitics compared to twin-well ones, making the design and optimization of these already complicated filters a rather difficult one. In this paper, we present a new Sinh lossy integrator circuit that uses (either N- or) P-type devices rendering it to be practically realizable in any standard twin-well process. The circuit has been designed in 0.35mum AMS CMOS process with all simulation results obtained from Cadence Design Frameworkreg. The resulting lossy integrator exhibits a simulated input dynamic range greater than 120dB with only one integrating capacitor, while dissipating 0.3muW of power.
    Circuits and Systems, 2007. ISCAS 2007. IEEE International Symposium on; 06/2007
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    ABSTRACT: We report the development of a new CNN based theoretical framework and its on-going analog VLSI implementation for continuous-time discrete-space spatiotemporal filtering. Our proposed formulation, which stems from the theory of linear cellular neural networks, is capable of realizing a wide range of linear spatiotemporal dynamics. Based on our proposed framework, 3D nonseparable spatiotemporal filters are synthesized. The filters are presented in the form of continuous-time/discrete-space mixed domain transfer functions with responses qualitatively resembling visual cortical bandpass spatiotemporal receptive fields. Analog VLSI building blocks suitable for the implementation of the required spatiotemporal dynamics are presented. Simulation results on AMS 0.35mum process parameters of a 5times5 array, with electrical parameters tuned to realize the spatiotemporal dynamics of one of our synthesized 3D bandpass filters, are presented
    Cellular Neural Networks and Their Applications, 2006. CNNA '06. 10th International Workshop on; 09/2006
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    ABSTRACT: This work presents the use of a two-layered recursive network to produce biomimetic visual spatiotemporal bandpass receptive fields. Simulation results of the transistor network based on an array of spatially coupled polyphase Gm-C filters are also included. Our bioinspired approach captures the essence of efficient processing in recursive cortical networks and at the same time backed by the vigorous analytical tools found in cellular neural network theory within the CAS community.
    Biomedical Circuits and Systems Conference, 2006. BioCAS 2006. IEEE; 01/2006
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    ABSTRACT: An analog network topology suitable for implementing continuous-time/discrete-space mixed domain rational spatiotemporal transfer functions is proposed. We also provide a generic VLSI-compatible implementation of the network based on continuous-time integrators. Numerical simulation results confirm the expected operation of a network realizing a first order velocity selective filter.
    Circuits and Systems, 2005. ISCAS 2005. IEEE International Symposium on; 06/2005
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    ABSTRACT: Oriented two dimensional spatial low-pass filters are useful for image processing tasks such as adaptive smoothing. We propose an oriented low-pass filter suitable for CNN implementations. The filter design procedure starts with an oriented Gaussian filter with the final CNN implementation involves only five non-zero coefficients in its feedback template, but achieving both orientation and scale tunable responses. By elaborating on the existing linear CNN stability criterion in terms of multidimensional signals theory, the stability of our CNN filter is also analyzed. Simulation results confirm the spatial impulse response of the CNN is indeed orientation and scale tunable.
    Circuits and Systems, 2005. 48th Midwest Symposium on; 01/2005