Mohamed Ben-Esmael
Lecturer in Electronics Engineering
School of Engineering, Computing and Mathematics
Role
Teaching Analogue Electronics and Physics and researcher in the Electronics and Instrumentation Group.
Research
Publications
Journal articles
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R. Nagulapalli, K. Hayatleh, S. Barker, A.A. Tammam, N. Yassine, B. Yassine, M. Ben-Esmael., 'A Low Noise Amplifier Suitable for Biomedical Recording Analog Front-End in 65nm CMOS Technology'
Journal of Circuits, Systems, and Computers 28 (8) (2018)
ISSN: 0218-1266 eISSN: 1793-6454AbstractThis paper presents a fully integrated Front-end, low noise amplifier, dedicated to the processing of various types of bio-medical signals, such as Electrocardiogram (ECG), Electroencephalography (EEG), Axon Action Potential (AAP). A novel noise reduction technique, for an operational transconductance amplifier (OTA), has been proposed. This adds a current steering branch parallel to the differential pair, with a view to reducing the noise contribution by the cascode current sources. Hence, this reduces the overall input referred noise of the Low Noise Amplifier (LNA), without adding any additional power. The proposed technique implemented in 65nm CMOS technology achieves 30dB closed loop voltage gain, 0.05Hz lower cut-off frequency and 100MHz 3-dB bandwidth. It operates at 1.2V power supply and draws 1µA static current. The prototype described in this paper occupies 3300µm2silicon area.Published here Open Access on RADAR -
Ben-Esmael M, Mathew M, Hart BL, Hayatleh K, 'Technique for increasing the output impedance of CMOS regulated cascode circuits.'
Journal of Circuits, Systems, and Computers 25 (10) (2016)
ISSN: 0218-1266 eISSN: 1793-6454AbstractA technique is proposed for the design of a modified CMOS regulated cascode having an output impedance significantly greater than that of a conventional regulated cascode. Simulation results for an illustrative design, operating at 10µA from a 1V supply, show an increase in output resistance from 636MΩ and output bandwidth of 55kHz for a conventional circuit to 6.68GΩ and 389kHz, respectively, for the proposed design.Published here Open Access on RADAR -
Tammam AA, Hayatleh K, Barker S, Ben-Esmael M, Terzopoulos N, 'Improved designs for current feedback op-amps'
International Journal of Electronics Letters 4 (2) (2015) pp.215-227
ISSN: 2168-1724AbstractThe performance of the current feedback op-amps (CFOAs) is very much determined by the input stage of CFOAs, including common-mode rejection ratio (CMRR). Two new CFOAs topologies are presented in this article: one topology uses a cascoding technique, and the second one uses a bootstrapping technique, both of which provide a much better CMRR and lower DC offset voltage than the conventional CFOAs. Moreover, the new CFOAs design exhibits an extended high frequency bandwidth, with a gain accuracy improvement. Applications requiring constant bandwidth with variable (closed loop) gain will benefit from the proposed topologies.Published here Open Access on RADAR -
Terzopoulos N, Hayatleh K, Sebu C, Lidgey FJ, Ben-Esmael M, Tammam AA, Barker S, 'Analysis and design of a high precision- high output impedance tissue current driver for medical applications'
Journal of Circuits, Systems, and Computers 23 (8) (2014)
ISSN: 0218-1266 eISSN: 1793-6454AbstractPublished here Open Access on RADARThis paper describes the design and operation of a high output impedance tissue current driver circuit, for use in medical electronics, such as Electrical Impedance Tomography (EIT). This novel architecture was designed for implementation in bipolar technology, to meet the specifications for EIT, namely operating frequency range 10 kHz–1 MHz with a target output resistance of 16 MW. Simulation results are presented, showing that the current source more than met the minimum specification for EIT.
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Ben-Esmael M, Hart BL, Hayatleh K, Lidgey FJ, 'CMRR-Bandwidth Extension Technique for CMOS Differential Amplifiers'
International Journal of Electronics and Communications 68 (10) (2014) pp.990-993
ISSN: 1434-8411AbstractPublished here Open Access on RADARAn exemplary design demonstrates how to extend the common-mode rejection ratio (CMRR) bandwidth of a CMOS differential amplifier. The design presented uses MOSFETs with a channel length of 180nm. A novel circuit technique is employed that partially compensates for the output capacitance of the tail current sink, thereby more than quadrupling the CMRR bandwidth in the example considered.
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Tammam AA, Hayatleh K, Sebu C, Lidgey FJ, Terzopoulos N, Ben-Esmael M, 'Wide-Bandwidth CFOA with High CMRR Performance'
International Journal of Electronics and Communications 68 (4) (2013) pp.329-335
ISSN: 1434-8411AbstractIn this paper the authors analyze the conventional current-feedback operational amplifier (CFOA) in terms of common-mode-rejection ratio (CMRR) performance, and having identified the mechanism primarily responsible for the CMRR, they propose two new architecture CFOAs. These new CFOAs are further developed, and modified to provide improved bandwidth, AC gain accuracy and high CMRR performance. The key features of the two proposed new CFOAs are the designs of the internal voltage followers which have two separate biasing currents with a similar dynamic architecture to that of the conventional CFOA. The magnitude of one bias current determines the value of the maximum CMRR, and the second can be used to maximize bandwidth.Published here Open Access on RADAR -
Ben-Esmael M, Lidgey FJ, Hayatleh K, Hart BL, 'Gain-bandwidth trade-off in the CMOS cascode amplifier'
Journal of Circuits, Systems, and Computers 22 (3) (2013)
ISSN: 0218-1266 eISSN: 1793-6454AbstractPublished hereThe cascode amplifier has the potential of providing high gain and high bandwidth simultaneously. However, the design is not as intuitive as one might at first think. In this paper, we present a detailed analysis of the single cascode amplifiers. The relationship between gain and bandwidth is important. When used to achieve maximum bandwidth the voltage gain of the common-source stage is close to unity. However, when the cascode is designed to obtain a high voltage gain, then the gain-bandwidth trade-off, typical in the common source amplifier, reappears. This analysis is used to provide the basis for practical cascode amplifier design.