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Design of digital to analog converter (dac) for integrated bluetooth applications using 0.18μm cmos technology / Low Pit Xing

Design of digital to analog converter (dac) for integrated bluetooth applications using 0.18μm cmos technology_Low Pit Xing_E3_2005_NI

Abstract Penukar isyarat digital ke analog (digital to analog converter, DAC) merupakan salah satu elemen yang penting dalam bidang perhubungan. Dalam projek ini, satu litar penukar isyarat digital ke analog yang beroperasi pada bekalan voltan 1.8V telah diimplementasikan berdasarkan proses teknologi Silterra CMOS 0.18μm. Penukar isyarat digital ke analog yang dibina ini adalah litar penukar masukan selari 8-bit jenis R-2R. Penukar isyarat digital ke analog ini berfungsi dengan satu voltan rujukan (Vref) dan mengeluarkan keluaran arus. Satu penguat kendalian (operational amplifier, op-amp) disambungkan pada hujung keluaran rangkaian R-2R untuk menukarkan arus keluaran ini kepada voltan keluaran yang sesuai. Litar penguat kendalian yang digunakan ini adalah jenis “cermin-arus” (current mirror) yang mempunyai gandaan voltan gelung terbuka 24.64dB. Di samping itu, penguat kendalian ini mempunyai lebar jalur 21.5MHz, dengan lesapan kuasa 0.85mW. Voltan rujukan kepada litar penukar pula dibekalkan oleh blok litar lain yang dikenali sebagai litar rujukan sela jalur (bandgap reference). Litar rujukan sela jalur ini terdiri transistor, penguat kendalian, perintang dan diod CMOS. Secara keseluruhannya, litar penukar isyarat digital ke analog itu mempunyai “settling time” 8ns, bermaksud kadar pensampelan data sebanyak 125MHz, dengan lesapan kuasa sebanyak 31.356mW. Skematik dan penyelakuan (atau simulasi) bagi seluruh litar adalah dilakukan dengan perisian komputer yang dikenali sebagai, Cadence, Virtuoso dan Spectre. _________________________________________________________________________________________ Digital to analog converter (DAC) is one of the important elements in the communication circuits. In this project, a digital to analog converter which operates with 1.8V voltage supply is implemented based on 0.18μm Silterra CMOS process technology. The implemented digital to analog converter is an 8-bit parallel inputs R-2R architecture converter. The digital to analog converter operates with a reference voltage and provides a current output. An operational amplifier is connected at the output end of the R-2R network to convert the output current to suitable output voltage. This operational amplifier is a current mirror op-amp with open loop dc voltage gain of 24.64dB. Besides, this op-amp achieves bandwidth of 21.5MHz, with the power consumption of 0.85mW. The mentioned reference voltage is established by another circuit block which known as bandgap reference voltage circuit. This bandgap reference voltage circuit is simply composed of CMOS transistors, op-amp, resistors and diodes. The overall D/A converter circuit has the settling time 8ns, which means the data sampling rate of 125MHz, with power consumption of 31.356mW. The schematic entry and simulation of the whole DAC circuits is done using the software Cadence, Virtuoso and Spectre.

Contributor(s): Low Pit Xing - Author Primary Item Type: Final Year Project Language: English Subject Keywords: communication circuits.; transistors,; op-amp, resistors and diodes. First presented to the public: 3/1/2005 Original Publication Date: 8/7/2018 Previously Published By: Universiti Sains Malaysia Place Of Publication: School of Electrical & Electronic Engineering Citation: Extents: Number of Pages - 75 License Grantor / Date Granted:   / ( View License ) Date Deposited 2018-08-07 15:10:43.181 Date Last Updated 2019-01-07 11:24:32.9118 Submitter: Nor Hayati Ismail

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