The work was based on digitally controlled oscillator for an all-digital PLL in 65nm process. Phase locked loop’s were used in most of the application for clock generation and recovery as well. As the technology grows faster in the existinggeneration, there has to be quick development with the technique. In such case ananalog PLL which was used earlier gradually getting converted to digital circuit.All-digital PLL blocks does the same work as an analog PLL blocks, but thecircuits and other control circuitry designed were completely in digital form, becausedigital circuit has many advantages over analog counterpart when they arecompared with each other. Digital circuit could be scaled down or scaled up evenafter the circuits were designed. It could be designed for low power supply voltageand easy to construct in a 65 nm process. The digital circuit was widely chosento make life easier. In most of the application PLL’s were used for clock and data recovery purpose,from that perspective jitter will stand as a huge problem for the designers. Themain aim of this thesis was to design a DCO that should bring down the jitter asdown as possible which was designed as standalone, the designed DCO would belater placed in an all-digital PLL. To understand the concept and problem aboutjitter at the early stage of the project, an analog PLL was designed in block leveland tested for different types of jitter and then design of a DCO was started. This document was about the design of a digitally controlled oscillator whichoperates with the center frequency of 2.145 GHz. In the first stage of the projectthe LC tank with NMOS structure was built and tested. In the latter stage the LCtank was optimized by using PMOS structure as negative resistance and eventuallyended up with NMOS and PMOS cross coupled structure. Tuning banks were oneof the main design in this project which plays a key role in locking the system ifthe DCO is placed in an all-digital PLL system. So, three types of tuning bankswere introduced to make the system lock more precisely. The control circuits andthe varactors built were all digital and hence it is called as digitally controlledoscillator. Digital control circuits, other sub-blocks like differential to single endedand simple buffers were also designed to optimize the signal and the results wereshown.DCO and tuning banks were tested using different types of simulation and were tested for different jitter qualities and analysis. The simulation results are shownin the final chapter simulation and results.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:liu-89134 |
| Date | January 2013 |
| Creators | Balasubramanian, Manikandan, Vijayanathan, Saravana Prabhu |
| Publisher | Linköpings universitet, Elektroniksystem, Linköpings universitet, Tekniska högskolan, Linköpings universitet, Elektroniksystem, Linköpings universitet, Tekniska högskolan |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
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