Browsing by Subject "Direct sampling"
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Item Circuit techniques for programmable broadband radio receivers(2013-12) Forbes, Travis Michael, 1986-; Gharpurey, RanjitThe functionality provided by mobile devices such as cellular phones and tablets continues to increase over the years, with integration of an ever larger number of wireless standards within a given device. In several of these designs, each standard supported by a device requires its own IC receiver to be mounted on the device’s PCB. In multistandard and multimode radios, it is desirable to integrate all receivers onto the same IC as the digital processors for the standards, in order to reduce device cost and size. Ideally all the receivers should also share a single signal chain. Since each standard has its own requirements for linearity and noise figure, and each standard operates at a different RF carrier frequency, implementing such a receiver is very challenging. Such a receiver could be theoretically implemented using a broadband mixing receiver or by direct sampling by a high-speed analog-to-digital converter (ADC). Broadband mixing requires the use of a harmonic rejection mixer (HRM) or tunable band pass filter to remove harmonic mixing effects, which in the past have suffered from a large primary clock tuning range and high power consumption. However, direct sampling of the RF input requires a high-speed ADC with large dynamic range which is typically limited by clock timing skew, clock jitter, or harmonic folding. In this dissertation, techniques for programmable broadband radio receivers are proposed. A local oscillator (LO) synthesis method within HRMs is proposed which reduces the required primary clock tuning range in broadband receivers. The LO synthesis method is implemented in 130-nm CMOS. A clocking technique is introduced within the two-stage HRM, which helps in achieving state-of-the-art harmonic rejection performance without calibration or harmonic filtering. An analog frequency synthesis based broadband channelizer is proposed using the LO synthesis method which is capable of channelizing a broadband input using a single mixing stage and primary clock frequency. A frequency-folded ADC architecture is proposed which enables high-speed sampling with high dynamic range. A receiver based on the frequency-folded ADC architecture is implemented in 65-nm CMOS and achieves a sample rate of 2-GS/s, a mean 49-dB SNDR, and 8.5-dB NF.Item Seismic and sparse data integration through the use of direct sampling(2013-12) Hampton, Travis Payton; Srinivasan, SanjayThe integration of seismic attributes and well data is an important step in the development of reservoir models. These models draw upon large data sets including information from well logs, production history, seismic interpretation, and depositional models. Modern integration techniques use the extensive data sets to develop precise models using complex workflows at increased cost of time and computational power. However, a gap exists in which a geostatistically driven procedure could integrate pattern statistics inferred from seismic images and those integrated from analogous geologic systems in order to develop spatially accurate reservoir models. Direct Sampling Seismic Integration Process, DSSIP, was first proposed by Henke and Srinivasan (2010) as an alternative to traditional seismic integration methods. The process provides a probabilistic mapping tool for fast reservoir analysis based on sparse conditioning data in a target reservoir and fully interpreted data from an analog field. DSSIP combines the structural information present in seismic data and facies patterns present in a training reservoir to create a fully realized output map for the target field. In this work, the basic DSSIP algorithm has been further optimized by performing a detailed parameter sensitivity study. The basic DSSIP algorithm has been demonstrated for a real field data set for a deepwater Gulf of Mexico reservoir. The basic DSSIP algorithm has also been analyzed to understand and model the effects of features such as salt canopy that can blur the seismic image. Finally, a modification to the basic algorithm is also presented that uses only a training model and the seismic data for the target reservoir in order to generate reservoir models for the target reservoir. This procedure eliminates the requirement to have a matching pair of training data sets for both the facies distribution and the corresponding seismic response.