Digital Calibration Algorithms for Nyquist-rate Analog to Digital Converters PDF Download
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Author: Anup Savla
Publisher:
ISBN:
Category : Analog-to-digital converters
Languages : en
Pages :
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Book Description
Abstract: Continuous scaling down of CMOS device sizes and an accompanied increase in device switching speeds prompts the design of mixed-signal systems with increasingly complex digital signal processing and control algorithms accompanied by simpler analog circuitry. Analog to digital converter (ADC) is an essential mixed-signal component of modern receivers, where signals sensed from the source are converted to digital for further signal processing on them. In this dissertation, calibration techniques are presented which allow ADCs to be designed with large inherent gain and offset errors. The concept of arbitrary radix multistep conversion is presented, along with algorithms that enable reduced radix conversion with digital correction in pipelined or algorithmic ADCs. Calibration techniques that account for linear and nonlinear gain error are presented and adapted to the popular 1.5 bit/stage pipeline architecture. Calibration is performed purely with digital post-processing on ADC output bits, with no changes occurring in the analog hardware. In this dissertation a WCDMA/WLAN receiver architecture is presented and specifications are derived for all its components. Concept of reconfigurable ADC design is presented, which allows speed and power consumption optimization. Reduced radix digital correction, linear and nonlinear calibration and background-calibrating queues are presented and combined in two behavioral models. The reconfigurable ADC was fabricated in AMI0.5u 3V CMOS process, and achieved 55dB dynamic range at 45MS/s, consuming 51mW power. The reconfigured calibrated ADC was simulated in TSMC 0.18u 1.8V CMOS process, and achieved 63dB dynamic range at 25MS/s, consuming 3.6mW power. Measurements of the capture card showed a 1.6bit improvement in resolution with the use of calibration algorithms.
Author: Anup Savla
Publisher:
ISBN:
Category : Analog-to-digital converters
Languages : en
Pages :
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Book Description
Abstract: Continuous scaling down of CMOS device sizes and an accompanied increase in device switching speeds prompts the design of mixed-signal systems with increasingly complex digital signal processing and control algorithms accompanied by simpler analog circuitry. Analog to digital converter (ADC) is an essential mixed-signal component of modern receivers, where signals sensed from the source are converted to digital for further signal processing on them. In this dissertation, calibration techniques are presented which allow ADCs to be designed with large inherent gain and offset errors. The concept of arbitrary radix multistep conversion is presented, along with algorithms that enable reduced radix conversion with digital correction in pipelined or algorithmic ADCs. Calibration techniques that account for linear and nonlinear gain error are presented and adapted to the popular 1.5 bit/stage pipeline architecture. Calibration is performed purely with digital post-processing on ADC output bits, with no changes occurring in the analog hardware. In this dissertation a WCDMA/WLAN receiver architecture is presented and specifications are derived for all its components. Concept of reconfigurable ADC design is presented, which allows speed and power consumption optimization. Reduced radix digital correction, linear and nonlinear calibration and background-calibrating queues are presented and combined in two behavioral models. The reconfigurable ADC was fabricated in AMI0.5u 3V CMOS process, and achieved 55dB dynamic range at 45MS/s, consuming 51mW power. The reconfigured calibrated ADC was simulated in TSMC 0.18u 1.8V CMOS process, and achieved 63dB dynamic range at 25MS/s, consuming 3.6mW power. Measurements of the capture card showed a 1.6bit improvement in resolution with the use of calibration algorithms.
Author: Rabeeh Majidi
Publisher:
ISBN:
Category :
Languages : en
Pages : 204
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Book Description
Abstract: With the advance of technology and rapid growth of digital systems, low power high speed analog-to- digital converters with great accuracy are in demand. To achieve high effective number of bits Analog-to-Digital Converter (ADC) calibration as a time consuming process is a potential bottleneck for designs. This dissertation presentsa fully digital background calibration algorithm for a 7- bit redundant flash ADC using split structure and look-up table based correction. Redundant comparators are used in the flash ADC design of this work in order to tolerate large offset voltages while minimizing signal input capacitance. The split ADC structure helps by eliminating the unknown input signal from the calibration path. The flash ADC has been designed in 180nm IBM CMOS technology and fabricated through MOSIS. This work was supported by Analog Devices, Wilmington, MA. While much research on ADC design has concentrated on increasing resolution and sample rate, there are many applications (e.g. biomedical devices and sensor networks) that do not require high performance but do require low power energy efficient ADCs. This dissertation also explores on design of a low quiescent current 100k Sps Successive Approximation (SAR) ADC that has been used as an error detection ADC for an automotive application in 350nm CD (CMOS-DMOS) technology. This work was supported by ON Semiconductor Corp, East Greenwich, RI.
Author: Hendrik van der Ploeg
Publisher: Springer Science & Business Media
ISBN: 1402046359
Category : Technology & Engineering
Languages : en
Pages : 203
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Book Description
This book analyses different A/D-converter architectures with an emphasis on the maximum achievable power efficiency. It also provides an accessible overview of the state-of-the art in calibration techniques for Nyquist A/D converters. The calibration techniques presented are applicable to other analog-to-digital systems, such as those applied in integrated receivers. They allow implementation without introducing a speed or power penalty.
Author: Ozan Ersan Erdoğan
Publisher:
ISBN:
Category :
Languages : en
Pages : 250
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Book Description
Author: Anu Kalidas Muralidharan Pillai
Publisher: Linköping University Electronic Press
ISBN: 9175190621
Category : Algorithms
Languages : en
Pages : 100
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Book Description
An analog-to-digital converter (ADC) is a key component in many electronic systems. It is used to convert analog signals to the equivalent digital form. The conversion involves sampling which is the process of converting a continuous-time signal to a sequence of discrete-time samples, and quantization in which each sampled value is represented using a finite number of bits. The sampling rate and the effective resolution (number of bits) are two key ADC performance metrics. Today, ADCs form a major bottleneck in many applications like communication systems since it is difficult to simultaneously achieve high sampling rate and high resolution. Among the various ADC architectures, the time-interleaved analog-to-digital converter (TI-ADC) has emerged as a popular choice for achieving very high sampling rates and resolutions. At the principle level, by interleaving the outputs of M identical channel ADCs, a TI-ADC could achieve the same resolution as that of a channel ADC but with M times higher bandwidth. However, in practice, mismatches between the channel ADCs result in a nonuniformly sampled signal at the output of a TI-ADC which reduces the achievable resolution. Often, in TIADC implementations, digital reconstructors are used to recover the uniform-grid samples from the nonuniformly sampled signal at the output of the TI-ADC. Since such reconstructors operate at the TI-ADC output rate, reducing the number of computations required per corrected output sample helps to reduce the power consumed by the TI-ADC. Also, as the mismatch parameters change occasionally, the reconstructor should support online reconfiguration with minimal or no redesign. Further, it is advantageous to have reconstruction schemes that require fewer coefficient updates during reconfiguration. In this thesis, we focus on reducing the design and implementation complexities of nonrecursive finite-length impulse response (FIR) reconstructors. We propose efficient reconstruction schemes for three classes of nonuniformly sampled signals that can occur at the output of TI-ADCs. Firstly, we consider a class of nonuniformly sampled signals that occur as a result of static timing mismatch errors or due to channel mismatches in TI-ADCs. For this type of nonuniformly sampled signals, we propose three reconstructors which utilize a two-rate approach to derive the corresponding single-rate structure. The two-rate based reconstructors move part of the complexity to a symmetric filter and also simplifies the reconstruction problem. The complexity reduction stems from the fact that half of the impulse response coefficients of the symmetric filter are equal to zero and that, compared to the original reconstruction problem, the simplified problem requires only a simpler reconstructor. Next, we consider the class of nonuniformly sampled signals that occur when a TI-ADC is used for sub-Nyquist cyclic nonuniform sampling (CNUS) of sparse multi-band signals. Sub-Nyquist sampling utilizes the sparsities in the analog signal to sample the signal at a lower rate. However, the reduced sampling rate comes at the cost of additional digital signal processing that is needed to reconstruct the uniform-grid sequence from the sub-Nyquist sampled sequence obtained via CNUS. The existing reconstruction scheme is computationally intensive and time consuming and offsets the gains obtained from the reduced sampling rate. Also, in applications where the band locations of the sparse multi-band signal can change from time to time, the reconstructor should support online reconfigurability. Here, we propose a reconstruction scheme that reduces the computational complexity of the reconstructor and at the same time, simplifies the online reconfigurability of the reconstructor. Finally, we consider a class of nonuniformly sampled signals which occur at the output of TI-ADCs that use some of the input sampling instants for sampling a known calibration signal. The samples corresponding to the calibration signal are used for estimating the channel mismatch parameters. In such TI-ADCs, nonuniform sampling is due to the mismatches between the channel ADCs and due to the missing input samples corresponding to the sampling instants reserved for the calibration signal. We propose three reconstruction schemes for such nonuniformly sampled signals and show using design examples that, compared to a previous solution, the proposed schemes require substantially lower computational complexity.
Author: Udaykiran Eduri
Publisher:
ISBN:
Category : Analog-to-digital converters
Languages : en
Pages : 182
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Book Description
Author: Yang Wu
Publisher:
ISBN:
Category :
Languages : en
Pages : 264
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Book Description
"The design details of pipeline ADC is also discussed in this work. Quantitative analyses have been provided in determining design parameters in various subsystems. The analyses ensure that a 10-bit resolution is achieved for the pipeline ADC. Both Flash ADC and pipeline ADC were implemented in a 0.25 mum and 0.18 mum CMOS process respectively, and results demonstrating their successful operation are presented." --
Author: Bardia Pishdad
Publisher:
ISBN:
Category :
Languages : en
Pages : 220
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Book Description
"Analog-to-Digital Converter (ADC) microcircuits are required to meet stringent accuracy specifications in spite of their analog components' inherent nonidealities as well as the accuracy limitations due to fabrication technology. In this thesis, a 3-step Nyquist rate ADC is presented which makes use of bitstream processing to calibrate the digital-to-analog converter (DAC) and the residue amplifier, while using the same hardware to calibrate the sub-ADC. The system is designed to provide programmability and calibrate undesired circuit characteristics such as offset, gain error, and nonlinearity. Thus, the DAC can tolerate gain errors much higher than the standard amount, and has the potential to completely cancel nonlinearity and offsets in its transfer function. The offset of the residue amplifier can also be calibrated with this system. Moreover, the system eliminates the need for a reference ladder in the sub-ADC, and calibrates comparator offsets. Simulation and experimental results of the circuits fabricated in a 0.18mum CMOS process are presented." --
Author: Shafiq M. Jamal
Publisher:
ISBN:
Category : Analog-to-digital converters
Languages : en
Pages : 262
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Book Description
Author: Manar El-Chammas
Publisher: Springer Science & Business Media
ISBN: 146141511X
Category : Technology & Engineering
Languages : en
Pages : 138
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Book Description
This book describes techniques for time-interleaving a number of analog-to-digital data converters to achieve demanding bandwidth requirements. Readers will benefit from the presentation of a low-power solution that can be used in actual products, while alleviating the time-varying signal artifacts that typically arise when implementing such a system architecture.
