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Design digital-to-analog converter and voltage-to-current converter in pixel readout circuit for x-ray images

Design digital-to-analog converter and voltage-to-current converter in pixel readout circuit for x-ray images / Nur Asma Hidayah Azmi
Dewasa ini, pengesan imej mendapat banyak tumpuan dalam aplikasi aplikasi seperti kamera, televisyen, telefon selular dan peralatan-peralatan lain. Aplikasi seperti ini secara dominan dicipta menggunakan transistor CMOS disebabkan kos yang rendah dan keperluan untuk memproses signal dengan bagus. Untuk imej x-ray, kajian secara berterusan dilakukan untuk memperolehi imej yang jelas mengenai struktur dalaman badan manusia. Imej x-ray berbeza bergantung kepada keamatan radiasi yang menembusi badan dan direkod menggunakan filem radiografi. Pengesan piksel secara digital digunakan untuk membaca imej bagi data kerana ini dapat mengurangkan hingar yang dihasilkan oleh litar analog. Setiap blok di dalam imej x-ray terdiri daripada fotopengesan dan penukar analog kepada digital (A/D) yang juga dipanggil penukar sigma delta. Penukar sigma delta pula terdiri daripada pengamir, pembanding, dan 1-bit penukar digital kepada analog (DAC). Kajian ini adalah untuk mencipta 1-bit DAC supaya sesuai digunakan bersama pengamir dan pembanding di dalam penukar sigma delta dengan kadar hingar yang rendah. Di akhir projek ini, DAC mencapai ralat ofset dan ralat gandaan sebanyak 290mLSB dan 0.286LSB. Penggunaan tenaga yang dihasilkan adalah lebih kurang 0.0302nW. Penukar voltan kepada arus juga ditambah dalam rekabentuk. Ia digunakan untuk menukar keluaran voltan kepada arus untuk dibaca. Projek ini menggunakan perisian Cadence 0.18um teknologi CMOS. _______________________________________________________________________________________________________ Image sensors have gained a lot of interest lately in many applications such as cameras, television, cellular phones, and other devices. These applications are predominantly designed by CMOS transistors due to low cost and good signal processing capability. For x-ray images, sequential series of study has been done to obtain clear image of an inner body structures. X-ray images can be varies depend on radiation intensity that passes through the body and recorded on radiographic film. Digital pixel sensor is used to read the data image because it can reduces the noise introduced by the commutations of the analog circuit. In each pixel blocks of x-ray image, it is consists by a photodetector and A/D converter which called sigma delta converter. The circuit of converter constitute of integrator, comparator,1-bit digital-to-analog converter (DAC). The research is to design 1-bit DAC so that it is compatible to use them along with integrator and comparator in sigma delta converter with low noise. Voltage to current converter (V/I) is also implemented in the design. It used to convert the voltage output to current output reading. At the end of this project, it is concluded that DAC can obtain offset error and gain error by 290.34mLSB and 0.286LSB. The power consumption produced for the whole circuit is around 0.0302nW. This project is done using Cadence Software in 0.18um CMOS technology.
Contributor(s):
Nur Asma Hidayah Azmi - Author
Primary Item Type:
Final Year Project
Identifiers:
Accession Number : 875004640
Barcode : 00003093643
Subject Keywords:
Image sensors; x-ray images; Digital pixel
First presented to the public:
6/1/2012
Original Publication Date:
3/15/2018
Previously Published By:
Universiti Sains Malaysia
Place Of Publication:
School of Electrical & Electronic Engineering
Citation:
Extents:
Number of Pages - 73
License Grantor / Date Granted:
  / ( View License )
Date Deposited
2018-03-15 12:34:32.474
Date Last Updated
2019-01-07 11:24:32.9118
Submitter:
Mohd Jasnizam Mohd Salleh

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Design digital-to-analog converter and voltage-to-current converter in pixel readout circuit for x-ray images1 2018-03-15 12:34:32.474