The Experts below are selected from a list of 29394 Experts worldwide ranked by ideXlab platform
Andrew J Mason - One of the best experts on this subject based on the ideXlab platform.
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process temperature variation tolerant precision Signal strength indicator
IEEE Transactions on Circuits and Systems, 2008Co-Authors: Chao Yang, Andrew J MasonAbstract:A Receiving Signal strength indicator (RSSI) built with transconductance amplifiers is presented. The RSSI achieves high tolerance to process/temperature variations by utilizing the unique nature of branch currents in a transconductance amplifier. These branch currents are used to implement a current-mode rectifier and amplitude clipping circuit that are tolerant of process variations. An on-chip offset control loop permits the entire RSSI to be realized with only one external component. In 0.18-mum CMOS with a 1.8 V supply, the RSSI draws 2.5 mA and provides 80 dB of offset suppression and more than 75 dB of log-linear range with less than +/ - 2-dB error due to process variation.
Ahmad K.a. - One of the best experts on this subject based on the ideXlab platform.
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Design and characterization piezoelectric acoustic transducer for sonar application
'Institute of Electrical and Electronics Engineers (IEEE)', 2019Co-Authors: Ahmad K.a., Hussain Z., Osman M.k., Abdullah M.f., Manaf A.a., Abdullah N.Abstract:Sonar system is one of the acoustic technologies that widely used in the underwater application. Sound Navigation and Ranging or SONAR is a technique to transmit and receive information using sound propagation. Besides that, sonar can be used in navigation, communication between underwater vehicles and detected the object under the surface of water. ROV or UAV will equipped with sonar transducer to recognize underwater object. The information from sonar transducer will build into images using some techniques of Signal processing. It is called underwater imaging. The sharp and clear image can be obtained from high resolution and good Receiving Signal. Thus, the sonar is equipped with an acoustic transducer that has a capability of high sensitivity and high bandwidth. The recent sonar don't have this capabilities, furthermore, it is bulky, high power consumption and expensive fabrication. This paper is presented design receiver of piezoelectric acoustic transducer (PAT) in small scale, inexpensive and not complex fabrication. PAT is designed using printed circuit board (PCB) as conductive part and substrate. Then, the piezoelectric material is used as sensing element and silicone glue is used to cover all conductive part. Polyvinylidene fluoride (PVDF) with thickness 110 um is transduced the vibration into electrical field. There are four differences design, with difference diameter of conductor, 8 mm, 7 mm, 6 mm, and 5 mm. Two experimental were conducted to test and characterize all PAT. They are called load test and pulse-echo method. Load test is conducted to see the behavior between mass of weight towards to PAT. Meanwhile, pulse-echo method is to characterize and see the performance of PAT. In load test result, the highest amplitude has been obtained by the design with diameter 5 mm, followed by 7 mm, 6 mm and the lowest amplitude is obtained by diameter 8 mm. The load test result has been proved using the equation 2, where the voltage is inversely proportional to their diameter of round shape. All these designs can be applied as load sensor, if used at the load weight from 0 to 50 gram. Design of PAT is used d31 mode polarization concept. This is a low cost fabrication design and high sensitivity. The design is solved the problem of an acoustic transducer with low sensitivity and narrow bandwidth. PAT is designed in small scale, and it is easy to assemble into AUV or ROV. The best design is with 5 mm, it has wide bandwidth and highest sensitivity. Then, the resonance frequency is at 125 kHz and output voltage at 555 mV. © 2018 IEEE
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Piezoelectric micromachined ultrasonic transducers array based on is mode polarization method
'Institute of Electrical and Electronics Engineers (IEEE)', 2018Co-Authors: Ahmad K.a., Janin Z., Hussain Z., Abd Manaf A.Abstract:Piezoelectric Micromachined Ultrasonic Transducer (PMUT) is a device used in many application such as medical diagnostic, medical acoustic imagine and underwater acoustic applications. Latest research, PMUT is investigated in marine application and underwater acoustic imaging. The important factor in underwater acoustic imaging is the image can capture very clear visibility. The acoustic transducer is very important to make sure that the acoustic Signal obtained has good sensitivity and wide operation bandwidth. Conventional underwater acoustic transducer used sandwich method. Then a latest researcher is investigated the microscale transducer called piezoelectric micromachined ultrasonic transducers to increase the performance of acoustic transducers. The conventional PMUT is still has limitation in sensitivity and bandwidth. The investigation of PMUT array based d33 mode polarization will improved the sensitivity of PMUT transducer. The fabrication of PMUT array based d33 mode polarization is simple fabrication. Experimental setup is used pulse-echo method to characterize the sensitivity of acoustic transducer inside water. The open circuit Receiving voltage (OCRV) is obtaining the Receiving Signal from acoustic transmitter. The PMUT array based d33 mode polarization shows it has more sensitive compare the conventional ultrasonic transducer. The design transducer has sensitivity at -56 dB re 1V/μPa at 100kHz and fractional bandwidth at 30. © 2017 IEEE
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D33 mode based piezoelectric micromachined ultrasonic transducers
'Institute of Electrical and Electronics Engineers (IEEE)', 2018Co-Authors: Ahmad K.a., Abdullah N., Manaf A.a.Abstract:Piezoelectric Micromachined Ultrasonic Transducer (PMUT) is an acoustic transducer used in application of medical diagnostic, medical imaging and underwater imaging. The design concept of conventional PMUT is based on sandwich piezoelectric between two electrodes. This is based on d31 mode polarization PMUT and the sensitivity is depend on thickness of piezoelectric and flexural deformation of membrane. The d33 mode polarization design concept is normally applied in energy harvester. This concept will increased the energy. This paper will present D33 mode based Piezoelectric Micromachined Ultrasonic Transducers to increase the sensitivity. Polyimide (PI) is used as membrane and substrate and dielectric help to increase the sensitivity. Pulse-Echo method is an experimental method to characterize the Receiving sensitivity. The simulation on PMUT design to see the peak displacement of PMUT and it will be represented as resonance frequency occurred in collecting Receiving Signal. The PMUT device has more Receiving sensitivity compared to conventional hydrophone and it is shows in result. The Receiving sensitivity achieved by PMUT is-64.44 dB re 1V/uPa. The fractional bandwidth for PMUT is 28. The operational bandwidth is needed to be improve for future design. © 2017 IEEE
Chao Yang - One of the best experts on this subject based on the ideXlab platform.
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process temperature variation tolerant precision Signal strength indicator
IEEE Transactions on Circuits and Systems, 2008Co-Authors: Chao Yang, Andrew J MasonAbstract:A Receiving Signal strength indicator (RSSI) built with transconductance amplifiers is presented. The RSSI achieves high tolerance to process/temperature variations by utilizing the unique nature of branch currents in a transconductance amplifier. These branch currents are used to implement a current-mode rectifier and amplitude clipping circuit that are tolerant of process variations. An on-chip offset control loop permits the entire RSSI to be realized with only one external component. In 0.18-mum CMOS with a 1.8 V supply, the RSSI draws 2.5 mA and provides 80 dB of offset suppression and more than 75 dB of log-linear range with less than +/ - 2-dB error due to process variation.
Keping Wang - One of the best experts on this subject based on the ideXlab platform.
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a cmos low power temperature robust rssi using weak inversion limiting amplifiers
Journal of Circuits Systems and Computers, 2013Co-Authors: Keping Wang, Xuemei Lei, Kiat Seng Yeo, Xiang Cao, Zhigong WangAbstract:This paper presents a low-power CMOS Receiving Signal strength indicator (RSSI). The main architecture of the circuit adopts a six-stage limiting amplifier (LA) in a logarithmic-linear form, which ...
Mark A Griswold - One of the best experts on this subject based on the ideXlab platform.
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on coil multiple channel transmit system based on class d amplification and pre amplification with current amplitude feedback
Magnetic Resonance in Medicine, 2013Co-Authors: Natalia Gudino, Jeremiah A Heilman, Matthew J Riffe, Oliver Heid, Markus Vester, Mark A GriswoldAbstract:A complete high-efficiency transmit amplifier unit designed to be implemented in on-coil transmit arrays is presented. High power capability, low power dissipation, scalability, and cost minimization were some of the requirements imposed to the design. The system is composed of a current mode class-D amplifier output stage and a voltage mode class-D preamplification stage. The amplitude information of the radio frequency pulse was added through a customized step-down DC-DC converter with current amplitude feedback that connects to the current mode class-D stage. Benchtop measurements and imaging experiments were carried out to analyze system performance. Direct control of B1 was possible and its load sensitivity was reduced to less than 10% variation from unloaded to full loaded condition. When using the amplifiers in an array configuration, isolation above 20 dB was achieved between neighboring coils by the amplifier decoupling method. High output current operation of the transmitter was proved on the benchtop through output power measurements and in a 1.5T scanner through flip angle quantification. Finally, single and multiple channel excitations with the new hardware were demonstrated by Receiving Signal with the body coil of the scanner. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.
