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Split Cyclic Analog to Digital Converter Using A Nonlinear Gain StageSpetla, Hattie 02 September 2009 (has links)
"Previous implementations of digital background calibration for cyclic ADCs have required linear amplifier behavior in the gain stage for accurate correction. Correction is digital decoding of ADC outputs to determine the original ADC input. Permitting nonlinearity in the gain stage of the ADC allows for less demanding amplifier design requirements, reducing power and size. However this requires a method of determining the value of this variable gain during digital correction. Look up tables (LUTs,) are an effective and efficient method of compensating for analog circuit imperfections. The LUT correction and calibration method discussed in this work has been simulated using Cadence integrated circuit simulation ADC specifications and MATLAB."
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Comparator-Based Cyclic Analog-to-Digital Conversion with Error-TrimmingChang, Li-Shen 11 August 2009 (has links)
This thesis focuses on the analysis theory, circuit design, simulations, and chip measurements of the transfer stage in the continuously error-trimming comparator-based switched-capacitor charge transfer stage in the cyclic redundant-sign-digit (RSD) algorithm.
Capacitor mismatching remains an insurmountable factor for switched-capacitor circuit designers. To correct errors which result from the capacitor mismatching, a continuous error-trimming circuit is generalized from a typical CBSC circuit. The
analysis theory of the error-trimming operation describes the effects of the error-trimming circuit in the CBSC circuit, as well as the guidelines for trimming. The error-trimming operation is able to tune the gain and virtual condition of the charge transfer stage for canceling the gain and offset errors. The circuit is designed, with the 0.35£gm 2-poly 4-metal TSMC process, in fully integral circuits. The circuit is
simulated by a matlab simulator and an online Cadence Spectre simulator, to confirm how the operation works. Finally, chip measurements are recorded for verification and simulation comparisons.
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Area Efficient ADC for Low Frequency ApplicationSami, Abdul Wahab January 2014 (has links)
Analog to digital converters (ADCs) are the fundamental building blocks in communication systems. The need to design ADCs, which are area and/or power efficient, has been common. Various ADC architectures, constrained by resolution capabilities, can be used for this purpose. The cyclic algorithmic architecture of ADC with moderate number of bits comes out to be probably best choice for the minimum area implementation. In this thesis a cyclic ADC is designed using CMOS 65 nm technology. The ADC high-level model is thoroughly explored and its functional blocks are modelled to attain the best possible performance. In particular, the nonlinearities which affect the cyclic/algorithmic converter are discussed. This ADC has been designed for built-in-self-testing (BiST) on a chip. It is only functional during the testing phase, so power dissipation is not a constraint while designing it. As it is supposed to be integrated as an extra circuitry on a chip, its area really matters. The ADC is designed as 10-bit fully differential switch-capacitor (SC) circuit using 65nm CMOS process with 1.2V power supply. A two stage Operational Transconductance Amplifier (OTA) is used in this design to provide sufficient voltage gain. The first stage is a telescopic OTA whereas the second is a common source amplifier. The bottom plate sampling is used to minimize the charge injection effect which is present in the switches.
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A Cyclic Analog to Digital Converter for CMOS image sensorsLevski Dimitrov, Deyan January 2014 (has links)
The constant strive for improvement of digital video capturing speeds together with power efficiency increase, has lead to tremendous research activities in the image sensor readout field during the past decade. The improvement of lithography and solid-state technologies provide the possibility of manufacturing higher resolution image sensors. A double resolution size-up, leads to a quadruple readout speed requirement, if the same capturing frame rate is to be maintained. The speed requirements of conventional serial readout techniques follow the same curve and are becoming more challenging to design, thus employing parallelism in the readout schemes appears to be inevitable for relaxing the analog readout circuits and keeping the same capturing speeds. This transfer however imposes additional demands to parallel ADC designs, mainly related to achievable accuracy, area and power. In this work a 12-bit Cyclic ADC (CADC) aimed for column-parallel readout implementation in CMOS image sensors is presented. The aim of the conducted study is to cover multiple CADC sub-component architectures and provide an analysis onto the latter to a mid-level of depth. A few various Multiplying DAC (MDAC) structures have been re-examined and a preliminary redundant signed-digit CADC design based on a 1.5-bit modified flip-over MDAC has been conducted. Three comparator architectures have been explored and a dynamic interpolative Sub-ADC is presented. Finally, some weak spots degrading the performance of the carried-out design have been analyzed. As an architectural improvement possibility two MDAC capacitor mismatch error reduction techniques have been presented.
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High Performance RF and Basdband Analog-to-Digital Interface for Multi-standard/Wideband ApplicationsZhang, Heng 2010 December 1900 (has links)
The prevalence of wireless standards and the introduction of dynamic
standards/applications, such as software-defined radio, necessitate the next generation
wireless devices that integrate multiple standards in a single chip-set to support a variety
of services. To reduce the cost and area of such multi-standard handheld devices,
reconfigurability is desirable, and the hardware should be shared/reused as much as
possible. This research proposes several novel circuit topologies that can meet various
specifications with minimum cost, which are suited for multi-standard applications. This
doctoral study has two separate contributions: 1. The low noise amplifier (LNA) for the
RF front-end; and 2. The analog-to-digital converter (ADC).
The first part of this dissertation focuses on LNA noise reduction and linearization
techniques where two novel LNAs are designed, taped out, and measured. The first LNA,
implemented in TSMC (Taiwan Semiconductor Manufacturing Company) 0.35Cm
CMOS (Complementary metal-oxide-semiconductor) process, strategically combined an
inductor connected at the gate of the cascode transistor and the capacitive cross-coupling
to reduce the noise and nonlinearity contributions of the cascode transistors. The proposed technique reduces LNA NF by 0.35 dB at 2.2 GHz and increases its IIP3 and
voltage gain by 2.35 dBm and 2dB respectively, without a compromise on power
consumption. The second LNA, implemented in UMC (United Microelectronics
Corporation) 0.13Cm CMOS process, features a practical linearization technique for
high-frequency wideband applications using an active nonlinear resistor, which obtains a
robust linearity improvement over process and temperature variations. The proposed
linearization method is experimentally demonstrated to improve the IIP3 by 3.5 to 9 dB
over a 2.5–10 GHz frequency range. A comparison of measurement results with the prior
published state-of-art Ultra-Wideband (UWB) LNAs shows that the proposed linearized
UWB LNA achieves excellent linearity with much less power than previously published
works.
The second part of this dissertation developed a reconfigurable ADC for multistandard
receiver and video processors. Typical ADCs are power optimized for only one
operating speed, while a reconfigurable ADC can scale its power at different speeds,
enabling minimal power consumption over a broad range of sampling rates. A novel
ADC architecture is proposed for programming the sampling rate with constant biasing
current and single clock. The ADC was designed and fabricated using UMC 90nm
CMOS process and featured good power scalability and simplified system design. The
programmable speed range covers all the video formats and most of the wireless
communication standards, while achieving comparable Figure-of-Merit with customized
ADCs at each performance node. Since bias current is kept constant, the reconfigurable
ADC is more robust and reliable than the previous published works.
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