[PDF] Integrated Photonic Analog To Digital Converters eBook

Author : Anatol M. Khilo
Publisher :
Page : 172 pages
File Size : 39,21 MB
Release : 2011
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Accurate conversion of wideband multi-GHz analog signals into the digital domain has long been a target of analog-to-digital converter (ADC) developers, driven by applications in radar systems, software radio, medical imaging, and communication systems. Aperture jitter has been a major bottleneck on the way towards higher speeds and better accuracy. Photonic ADCs, which perform sampling using ultra-stable optical pulse trains generated by mode-locked lasers, have been investigated as a promising approach to overcome the jitter problem and bring ADC performance to new levels. This work demonstrates that the photonic approach can deliver on its promise by digitizing a 41 GHz signal with 7.0 effective bits and 52 dBc spur-free dynamic range (SFDR) using a discrete-component photonic ADC. This corresponds to 15 fs jitter, a 4-5 times improvement over the jitter of the best electronic ADCs, and an order of magnitude improvement over the jitter of electronic ADCs operating above 10 GHz. The feasibility of a practical photonic ADC is demonstrated by creating an integrated ADC with a modulator, filters, and photodetectors fabricated on a single silicon chip and using it to sample a 10 GHz signal with 3.5 effective bits and 39 dBc SFDR. In both experiments, a sample rate of 2.1 GSa/s was obtained by interleaving two 1.05 GSa/s channels; higher sample rates can be achieved by increasing the channel count. A key component of a multi-channel ADC - a dual multi-channel high-performance filter bank - is successfully implemented. A concept for broadband linearization of the silicon modulator, which is another critical component of the photonic ADC, is proposed. Nonlinear phenomena in silicon microring filters and their impact on ADC performance are analyzed, and methods to reduce this impact are proposed. The results presented in the thesis suggest that a practical integrated photonic ADC, which successfully overcomes the electronic jitter bottleneck, is possible today.

Author : Barry L. Shoop
Publisher : Springer
Page : 341 pages
File Size : 27,40 MB
Release : 2012-11-02
Category : Technology & Engineering
ISBN : 3540444084

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Provides a comprehensive look at the application of photonic approaches to the problem of analog-to-digital conversion. It looks into the progress made to date, discusses present research, and presents a glimpse of potential future technologies.

Author : Michael Yung Peng
Publisher :
Page : 86 pages
File Size : 21,10 MB
Release : 2011
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ISBN :

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The performance of electronic analog-to-digital converters (ADCs) at high sampling rates is fundamentally limited by the timing jitter of electronic clocks. To circumvent this limitation, one method is to exploit the orders-of-magnitude lower timing jitter of mode-locked lasers and implement optical sampling as a front-end for electronic ADCs. The optical-sampling, wavelength-demultiplexing approach to A/D conversion, which is explored in this thesis, offers key benefits such as ease of scalability to higher aggregate sampling rates via passive wavelength-division demultiplexing (WDM) filters and potential for full integration via silicon photonics platform for chip-scale signal processing applications. This thesis will first cover the design issues for each stage in the optically-sampled, wavelength-demultiplexed photonic ADC architecture, followed by experimental results from two system demonstrations. Digitization of a 41-GHz signal with 7.0 effective bits at a sampling rate of 2 GSa/s was demonstrated with a discrete-component photonic ADC, which corresponds to 15 fs of jitter, a 4-5 times improvement over state-of-the-art electronic ADCs. On the way towards an integrated photonic ADC, a silicon chip with core photonic components was fabricated and used to digitize a 10-GHz signal with 3.5 effective bits. Drop-port transmission measurements of an integrated 20-channel WDM filter bank are included to show potential for high sampling rate operation with 10 effective bits.

Author : Oğuzhan Uyar
Publisher :
Page : 80 pages
File Size : 11,26 MB
Release : 2011
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As the resolution of electrical ADCs gets limited at higher sampling rates due to sampling clock jitter, low-jitter mode-lock laser based photonic ADCs are starting to gain more attention. As well as low-jitter and high-linearity operation at very high speeds, photonic ADCs provide the opportunity to de-multiplex electrical signals to enable the parallel sampling of signals which increases the total sampling speed dramatically. However, even in photonic systems, a careful optimization between the degree of de-multiplexing, the optical non-linearities and receiver front-end noise has to be performed to enable resolution and sampling rate gains to materialize. Electrical components still constitute the bottleneck for a photonic ADC system. Photo-detector front-end, which is responsible for the current-voltage transformation of the samples, is one of the most critical components for the overall linearity, noise and jitter performance of photonic ADC systems. This work focuses on photo-detector front-ends and investigates the performance of several structures as well as evaluating the performance of photonic ADC systems depending on the amount of photo-detector current. Integrator and trans-impedance amplifier flavors of the front-end circuits are designed, implemented, simulated and laid out for 6 ENOB and 10 ENOB linearity and noise performance at 1GS/s. The circuits are implemented on 45 nm SOI process and integrated with on-chip photonic components which allow on-chip and off-chip ADC implementations.

Author :
Publisher :
Page : 75 pages
File Size : 45,90 MB
Release : 2005
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A photonic analog-to-digital converter (ADC) based on a robust symmetrical number system (RSNS) was constructed and tested. The analog signal to be converted is used to amplitude modulate an optical pulse from a laser using three Mach-Zehnder interferometers (MZI). The Mach-Zehnder interferometers fold the input analog signal for a three-channel RSNS encoding. The folding waveforms are then detected and amplitude-analyzed by three separate comparator banks, the outputs of which are used to determine a digital representation of the analog signal. This design uses the RSNS preprocessing to encode the signal with the fewest number of comparators for any selected bit resolution. In addition to the efficiency of its use of comparators, the RSNS encoding has inherent Gray-code properties making it particularly attractive for eliminating any possible encoding errors. The RSNS encoding is combined with an optical infrastructure that offers high bandwidth and low insertion loss characteristics. A full implementation was constructed and tested. The lack of a high-speed data acquisition device limited the results to examining the preprocessing and digital processing separately. With the system integration of a data acquisition device, a wideband direct digital antenna architecture can be demonstrated.

Author :
Publisher :
Page : 57 pages
File Size : 37,77 MB
Release : 2005
Category : Analog-to-digital converters
ISBN :

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A photonic analog-to-digital converter (ADC) based on a robust symmetrical number system (RSNS) was constructed and tested. The analog signal to be converted is used to amplitude modulate an optical pulse from a laser using three Mach-Zehnder interferometers (MZI). The Mach-Zehnder interferometers fold the input analog signal for a three-channel RSNS encoding. The folding waveforms are then detected and amplitude-analyzed by three separate comparator banks, the outputs of which are used to determine a digital representation of the analog signal. This design uses the RSNS preprocessing to encode the signal with the fewest number of comparators for any selected bit resolution. In addition to the efficiency of its use of comparators, the RSNS encoding has inherent Gray-code properties making it particularly attractive for eliminating any possible encoding errors. The RSNS encoding is combined with an optical infrastructure that offers high bandwidth and low insertion loss characteristics. A full implementation was constructed and tested. The lack of a high-speed data acquisition device limited the results to examining the preprocessing and digital processing separately. With the system integration of a data acquisition device, a wideband direct digital antenna architecture can be demonstrated.

Author :
Publisher :
Page : 86 pages
File Size : 30,21 MB
Release : 2003
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This project demonstrates three photonic analog-digital converters (ADCs) for high-speed, real-time digitization of microwave signals. The methods consist of a highly parallel photonic ADC, a time-division multiplexed system based on electro-optical Sagnac interferometry, and an alloptical quantizer based upon distributed phase modulation. The core of many photonic ADC designs relies upon a low-noise, actively modelocked fiber laser that has been developed at NRL. Photonic sampling of microwave signals is investigated especially concerning development of a low-noise optical clock. Optimization and system post-processing is simulated and compared with experimental data. Finally, the low-noise optical clock was used in a four-way collaborative research effort where NRL excited and characterized high-speed, high-current photoconductive switches.