Izzet Kale

Approximation of FIR by IIR digital filters: an algorithm based on balanced model reduction

An algorithm for the approximation of finite impulse response (FIR) filters by infinite impulse response (IIR) filters is presented. The algorithm is based on a concept of balanced model reduction. The matrix inversions normally associated with this procedure are notoriously error prone due to ill conditioning of the special matrix forms required. This difficulty is circumvented here by directly formulating a reduced state-space system description which is input/output equivalent to the system that would more conventionally be obtained following the explicit step of constructing an (interim) balanced realization. Examples of FIR by IIR filter approximations are included. >

Designing multiplier blocks with low logic depth

The depth of logic in an integrated circuit, particularly a CMOS circuit, is highly correlated both with power consumption and degraded switching speed. Hence, designs with low logic depth can aid in reducing power consumption and increasing switching speed. In this paper we demonstrate how new and modified algorithms have been used to design multiplier blocks with low logic depth and power consumption.

Computer vision for microscopy diagnosis of malaria

This paper reviews computer vision and image analysis studies aiming at automated diagnosis or screening of malaria infection in microscope images of thin blood film smears. Existing works interpret the diagnosis problem differently or propose partial solutions to the problem. A critique of these works is furnished. In addition, a general pattern recognition framework to perform diagnosis, which includes image acquisition, pre-processing, segmentation, and pattern classification components, is described. The open problems are addressed and a perspective of the future work for realization of automated microscopy diagnosis of malaria is provided.

Parasite detection and identification for automated thin blood film malaria diagnosis

This paper investigates automated detection and identification of malaria parasites in images of Giemsa-stained thin blood film specimens. The Giemsa stain highlights not only the malaria parasites but also the white blood cells, platelets, and artefacts. We propose a complete framework to extract these stained structures, determine whether they are parasites, and identify the infecting species and life-cycle stages. We investigate species and life-cycle-stage identification as multi-class classification problems in which we compare three different classification schemes and empirically show that the detection, species, and life-cycle-stage tasks can be performed in a joint classification as well as an extension to binary detection. The proposed binary parasite detector can operate at 0.1% parasitemia without any false detections and with less than 10 false detections at levels as low as 0.01%.

Malaria Parasite Detection in Peripheral Blood Images

This paper investigates the possibility of computerised diagnosis of malaria and describes a method to detect malaria parasites (Plasmodium spp) in images acquired from Giemsa-stained peripheral blood samples using conventional light microscopes. Prior to processing, the images are transformed to match a reference image colour characteristics. The parasite detector utilises a Bayesian pixel classifier to mark stained pixels. The class conditional probability density functions of the stained and the non-stained classes are estimated using the non-parametric histogram method. The stained pixels are further processed to extract features (histogram, Hu moments, relative shape measurements, colour auto-correlogram) for a parasite/non-parasite classifier. A distance weighted K-nearest neighbour classifier is trained with the extracted features and a detailed performance comparison is presented. Our method achieves 74% sensitivity, 98% specificity, 88% positive prediction, and 95% negative prediction values for the parasite detection.

Rigorous analysis of delta-sigma modulators for fractional-N PLL frequency synthesis

In this paper, rigorous analyses are presented for higher order multistage noise shaping (MASH) Delta-Sigma (/spl Delta//spl Sigma/) modulators, which are built out of cascaded first-order stages, with rational DC inputs and nonzero initial conditions. Asymptotic statistics such as the mean, average power, and autocorrelation of the binary quantizer error are formulated using a nonlinear difference equation approach. An important topic of interest considered here is the fractional-N phase-locked-loop frequency synthesis applications, where the input to the modulator has to be a rational constant. It has been mathematically shown that, regardless of the initial conditions, first-order and second-order MASH /spl Delta//spl Sigma/ modulators with rational DC inputs cannot sufficiently randomize the quantization error samples, and, therefore, are not suitable for fractional-N synthesis applications. An irrational initial condition imposed on the first accumulator of a third or higher order MASH modulator, on the other hand, annihilates the tones throughout the whole output spectrum, and provides a very smooth noise shaping. Simulation results are provided to support the theoretically derived results. Implementation issues of the irrational initial condition in the digital domain are also discussed and investigated together with the effect of finite accumulator size on the noise-shaping quality factor.

Design of a 0.8 Volt fully differential CMOS OTA using the bulk-driven technique

This paper explores and presents the possible approaches to the design of a low-voltage operational transconductance amplifier (OTA) using the bulk-driven technique. The design of a 0.8 V fully differential folded-cascode OTA using a 0.35 /spl mu/m CMOS technology having a threshold voltage of 0.6 V is presented. This OTA utilizes bulk-driven differential-pairs to achieve rail-to-rail input operation, and gate- and bulk-biased cascode transistors to increase the output resistance. A continuous-time common-mode feedback (CMFB) is used for this OTA, which implements the bulk-driven differential pairs to sense the common-mode voltage smaller than the transistors threshold voltage, as well as bulk-driven current mirrors to reduce voltage headroom consumption. This OTA has been designed using Alcatels 0.35 /spl mu/m twin-well CMOS technology, and the simulation results indicate an open-loop gain>60 dB, unity gain-bandwidth=3.4 MHz with a 5 pF load, and an input common mode range (ICMR) of 0.8 V.

A pipelined noise shaping coder for fractional-N frequency synthesis

In this paper, we present the design considerations and implementation aspects of a pipelined all-digital fourth-order multi-stage-noise-shaping (MASH) delta-sigma (/spl utri//spl Sigma/) modulator suitable for fractional-N (F-N) phase-locked loop (PLL) frequency synthesis applications. In an effort to reduce the hardware complexity and power consumption, the alignment registers, which are normally required in pipelined adders, are eliminated by taking advantage of static modulator input. The MASH modulator has successfully been targeted to an Altera/sup TM/ field-programmable-gate-array (FPGA) device. The functional operation of the modulator has been verified through structural bit-level simulations as well as experimental results on the actual FPGA implementation.

Finite-precision Goertzel filters used for signal tone detection

The effect of coefficient quantization on the output of a second-order Goertzel filter tone-detector is analyzed in order that the Goertzel filter may be systematically designed for minimum complexity. Three alternative configurations are identified for the Goertzel filters component second-order digital resonator, which are especially suited to VLSI implementation, and which complement each other on the zero-to-Nyquist frequency interval. The Goertzel filters tone response is formulated using the Fourier summation transform (and shown to depend on both the frequency and phase of the incident tone). Hence analytic expressions are derived for the tone response of a fully finite-precision Goertzel filter when used with either a rectangular or half-end-point, input data window. These formulas are amenable to optimization, and are applied to improve a DTMF receiver design which is subject to the use of low-complexity second-order resonators.

BLOOD CELL SEGMENTATION USING MINIMUM AREA WATERSHED AND CIRCLE RADON TRANSFORMATIONS

In this study, a segmentation method is presented for the images of microscopic peripheral blood which mainly contain red blood cells, some of which contain parasites, and some white blood cells. The method uses several operators based on mathematical morphology. The cell area information which is estimated using the area granulometry (area pattern spectrum) is used for several steps in the method. A modified version of the original watershed algorithm [31] called minimum area watershed transform is developed and employed as an initial segmentation operator. The circle Radon transform is applied to the labelled regions to locate the cell centers (markers). The final result is produced by applying the original marker controlled watershed transform to the Radon transform output with its markers obtained from the regional maxima. The proposed method can be applied to similar blob object segmentation problems by adapting red blood cell characteristics for the new blob objects. The method has been tested on a benchmark set and scored a successful correct segmentation rate of 95.40%.