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| dc.contributor.author | Tesfu, Fiseha | |
| dc.date.accessioned | 2022-12-31T07:55:36Z | |
| dc.date.available | 2022-12-31T07:55:36Z | |
| dc.date.issued | 2022-11 | |
| dc.identifier.uri | http://ir.bdu.edu.et/handle/123456789/14813 | |
| dc.description.abstract | Ultrasound imaging has a widespread application in industrial and biomedical applications and in particular, portable/miniaturized ultrasound imaging systems are gaining popularity in point-of-care diagnostics. However, miniaturizing an ultrasound imaging system is very challenging because of the multidimensional tradeoffs inherent in the design. A careful balance of design tradeoffs, such as power consumption, chip area, bandwidth, and cost is essential. Since modern scanners rely heavily on digital signal processing, it is preferable to convert the ultrasound signal to a digital domain as early as possible in the system. However, this requires prior amplification with analog low-noise amplifiers to meet the dynamic range, bandwidth, and SNR requirements. Hence, a transistor-level design of Analog Front End (AFE) circuit with 90 nm CMOS technology is presented. The design is intended to have wide gain variation, small area, low power, low noise, and a wide dynamic range. The proposed AFE comprises of a low noise variable gain amplifier followed by an auxiliary programmable gain amplifier and a low pass filter. A common mode feedback circuit is designed for each of the fully differential amplifier stages to stabilize the output common mode voltage under variations in bias currents and voltage. To compensate for exponential signal attenuation as a function of imaging depth, the design adopts a linear in dB time-gain compensation circuitry. The AFE circuitry is designed and simulated in OrCAD Capture CIS Lite by integrating BSIM3 SPICE model for 90 nm CMOS process to MbreakN and MbreakP transistors from breakout library of PSPICE model. The simulation results show that in addition to providing 46dB gain, the front-end circuitry is capable of compensating the exponential signal attenuation as a function of tissue imaging depth with a tunable gain range of 23dB. The pramplifier consumes 0.6 mW power with a 1.2V supply. The measured input referred noise of the preamplifier is 3.6 𝑜𝑤 √𝐼𝑧 and the dynamic range is 62 dB, significantly better compared to designs in the literature. The programmable gain amplifier enables selection of three gain values: 16 dB, 20 dB, and 26 dB. Having a benefit of overall performance enhancement and chip area reduction, the thesis contributes to the research and development efforts of portable ultrasound imaging systems. Key-words: AFE, Miniaturization, CMOS, noise Figure, MbreakN, and MbreakP | en_US |
| dc.language.iso | en_US | en_US |
| dc.subject | ELECTRICAL AND COMPUTER ENGINEERING | en_US |
| dc.title | DESIGN OF ANALOG FRONT-END FOR PORTABLE ULTRASOUND IMAGING SYSTEMS | en_US |
| dc.type | Thesis | en_US |
