Elektrik- Elektronik Mühendisliği
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Browsing Elektrik- Elektronik Mühendisliği by Subject "Analog electronic systems -- Design and construction."
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Item An analog template router based on layout description script (LDS)(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 2014., 2014.) Sümengen, Cem.; Dündar, Günhan,Long design-test cycles in full-custom design process leads to high design costs in analog circuit design. The objective of design automation is to decrease the design cost and the time to market by reducing the time spent in the design process. Template-based tools have an advantage of requiring lower computational time by utilizing stored design knowledge. This property makes template based design techniques very appealing for some applications such as porting a design to di erent technologies or making minor changes on the design in the same technology. Unutulmaz et al. (2011) presented a declarative language to de ne layout templates for analog circuits, named Layout Description Script (LDS). In this study, a template router is proposed which outputs routing information for layout templates coded in LDS. The output of the router is exible routing information also coded in LDS. It is shown that the layout instances created from the output template with routing information can adapt itself to the changes in the dimensions of the circuit elements. Therefore, the template can be used by design automation tools in a closed optimization loop. The router proposed in this thesis di ers from the other routers by the nature of it's input and output. The input le holds the relative placement information of the circuit elements rather than providing xed coordinates in the layout. Likewise, the output le consists of relative positions of the interconnect and is self-adapting for the variations in dimensions of the circuit elements.Item Efficient yield estimation using rare event simulation techniques on analog design automation tools(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 2016., 2016.) Çamlı, Alphan.; Dündar, Günhan,With the improvements in fabrication processes, electronic circuit designers have begun to design complex circuits which consist of multibillion transistors. But, as circuit complexity increases, the silicon complexity also increases, leading to process variations having a profound effect on the circuit performance especially in sub micron technologies. Therefore, even if a circuit was designed to achieve a certain design specification, there will be a discrepancy between the simulated and the measured performances. This difference can lead to a decrease in the yield. Circuit designers tend to handle this problem by leaving a safety margin; however, this leads to overdesign and loss of precious chip area. Therefore, there is an undeniable need to have efficient design automation tools for reducing design time without compromising performance. Normally, a typical approach for analyzing a circuit would be running a Monte Carlo simulation with a small sample size and then fitting a standard analytical distribution to the data. Such an approach can be accurate for the main part of the distribution, however it will be heavily inaccurate in the tail of the distribution. Since, the distribution of design specifications with respect to process variation effects tends to have a long tail by nature, a classic Monte Carlo simulation can not be used. In this case, a rare event sampling method can be utilized for increasing number of samples corresponding to tail of the original distribution. Cross entropy minimization based importance sampling (IS) method is chosen as rare event sampling method for the scope of this thesis due to its efficiency, although there are lots of different Monte Carlo based proposals. Also, a hybrid Quasi-Monte Carlo (QMC) method has been utilized in order to both select rare event threshold that is needed for cross entropy based IS algorithm and performance comparison with the proposed algorithm.Item Novel design methods for analog design automation tools(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 2015., 2015.) Berkol, Gönenç.; Dündar, Günhan,; Başkaya, Faik.Improvements in fabrication processes have enabled designers to bene t from sub-micron devices, which have led to the integration of multibillion transistors. However, circuit complexity increases together with the silicon complexity, since the e ect of process variations in sub micron technologies are drastically increased. Thus, design automation tools have emerged to reduce design time without sacri cing performances. To achieve that goal, simulation based optimization algorithms for analog circuit circuits are developed in this thesis. In order to synthesize a robust circuit, yield is de ned as a new design objective, which is tried to be maximized during the optimization process. To enhance the e ciency of yield estimation, Quasi-Monte Carlo (QMC) method, has been utilized in optimization. In addition, since QMC is deterministic and has no natural variance, there is no convenient way to obtain error bounds for the estimation. To determine the con dence interval of the estimated yield, scrambled-QMC method and conventional QMC method are combined. Therefore, a hybrid method is proposed, where a single QMC is performed to determine infeasible solutions in terms of yield, which is followed by a few scrambled QMC analyses providing variance and con dence interval of the estimated yield. In addition to the variation-aware tools, a layout-aware tool is proposed, in which a simulation-based circuit sizing tool with a template based layout generation tool are combined. The layout-induced parasitics are automatically extracted and are taken into account during the optimization process. To reduce the run time cost due to parasitic extraction, a two step methodology is developed. Finally, the circuits obtained at the end of optimization are implemented as an integrated circuit to show the e ectiveness of the algorithms.