6 research outputs found
High-speed optical data transmission for detector instrumentation in particle physics
This work discusses the advantage of optical transmission utilizing wavelength-division multiplexing for the read-out of experimental data in detector instrumentation in high-energy physics, astroparticle physics or photon science. A multi-channel optical transmitter is developed as the core component on a silicon-on-insulator platform. It implements Mach-Zehnder modulators with a depletion-type pn-phase shifter in each arm, while the (de )multiplexers rely on planar concave gratings. The modulator design is expected to support a symbol rate in the range 40 GBd even with a phase shifter length of 3 mm. The development of an efficient simulation method is presented, which allows for the reliable prediction of the steady-state modulator characteristics. Furthermore, this work addresses the packaging technology for grating-coupled silicon photonic components. In particular, a fabrication and assembly process for a planar fiber-to-chip coupling using angle-polished single-mode fibers is developed. A long-term-stable coupling with a small footprint is achieved, of which the coupling efficiency is only weakly dependent on ambient conditions
Toward realizing power scalable and energy proportional high-speed wireline links
Growing computational demand and proliferation of cloud computing has placed high-speed
serial links at the center stage. Due to saturating energy efficiency improvements over the
last five years, increasing the data throughput comes at the cost of power consumption. Conventionally, serial link power can be reduced by optimizing individual building blocks such as
output drivers, receiver, or clock generation and distribution. However, this approach yields
very limited efficiency improvement. This dissertation takes an alternative approach toward
reducing the serial link power. Instead of optimizing the power of individual building blocks,
power of the entire serial link is reduced by exploiting serial link usage by the applications.
It has been demonstrated that serial links in servers are underutilized. On average, they
are used only 15% of the time, i.e. these links are idle for approximately 85% of the time.
Conventional links consume power during idle periods to maintain synchronization between
the transmitter and the receiver. However, by powering-off the link when idle and powering
it back when needed, power consumption of the serial link can be scaled proportionally to
its utilization. This approach of rapid power state transitioning is known as the rapid-on/off
approach. For the rapid-on/off to be effective, ideally the power-on time, off-state power,
and power state transition energy must all be close to zero. However, in practice, it is very
difficult to achieve these ideal conditions. Work presented in this dissertation addresses these
challenges.
When this research work was started (2011-12), there were only a couple of research papers
available in the area of rapid-on/off links. Systematic study or design of a rapid power state
transitioning in serial links was not available in the literature. Since rapid-on/off with
nanoseconds granularity is not a standard in any wireline communication, even the popular
test equipment does not support testing any such feature, neither any formal measurement methodology was available. All these circumstances made the beginning difficult. However,
these challenges provided a unique opportunity to explore new architectural techniques and
identify trade-offs. The key contributions of this dissertation are as follows.
The first and foremost contribution is understanding the underlying limitations of saturating energy efficiency improvements in serial links and why there is a compelling need to
find alternative ways to reduce the serial link power.
The second contribution is to identify potential power saving techniques and evaluate the
challenges they pose and the opportunities they present.
The third contribution is the design of a 5Gb/s transmitter with a rapid-on/off feature.
The transmitter achieves rapid-on/off capability in voltage mode output driver by using
a fast-digital regulator, and in the clock multiplier by accurate frequency pre-setting and
periodic reference insertion. To ease timing requirements, an improved edge replacement
logic circuit for the clock multiplier is proposed. Mathematical modeling of power-on time
as a function of various circuit parameters is also discussed. The proposed transmitter
demonstrates energy proportional operation over wide variations of link utilization, and is,
therefore, suitable for energy efficient links. Fabricated in 90nm CMOS technology, the
voltage mode driver, and the clock multiplier achieve power-on-time of only 2ns and 10ns,
respectively. This dissertation highlights key trade-off in the clock multiplier architecture,
to achieve fast power-on-lock capability at the cost of jitter performance.
The fourth contribution is the design of a 7GHz rapid-on/off LC-PLL based clock multi-
plier. The phase locked loop (PLL) based multiplier was developed to overcome the limita-
tions of the MDLL based approach. Proposed temperature compensated LC-PLL achieves
power-on-lock in 1ns.
The fifth and biggest contribution of this dissertation is the design of a 7Gb/s embedded
clock transceiver, which achieves rapid-on/off capability in LC-PLL, current-mode transmit-
ter and receiver. It was the first reported design of a complete transceiver, with an embedded
clock architecture, having rapid-on/off capability. Background phase calibration technique in
PLL and CDR phase calibration logic in the receiver enable instantaneous lock on power-on.
The proposed transceiver demonstrates power scalability with a wide range of link utiliza-
tion and, therefore, helps in improving overall system efficiency. Fabricated in 65nm CMOS technology, the 7Gb/s transceiver achieves power-on-lock in less than 20ns. The transceiver
achieves power scaling by 44x (63.7mW-to-1.43mW) and energy efficiency degradation by
only 2.2x (9.1pJ/bit-to-20.5pJ/bit), when the effective data rate (link utilization) changes
by 100x (7Gb/s-to-70Mb/s).
The sixth and final contribution is the design of a temperature sensor to compensate
the frequency drifts due to temperature variations, during long power-off periods, in the
fast power-on-lock LC-PLL. The proposed self-referenced VCO-based temperature sensor
is designed with all digital logic gates and achieves low supply sensitivity. This sensor is
suitable for integration in processor and DRAM environments. The proposed sensor works
on the principle of directly converting temperature information to frequency and finally
to digital bits. A novel sensing technique is proposed in which temperature information
is acquired by creating a threshold voltage difference between the transistors used in the
oscillators. Reduced supply sensitivity is achieved by employing junction capacitance, and
the overhead of voltage regulators and an external ideal reference frequency is avoided. The
effect of VCO phase noise on the sensor resolution is mathematically evaluated. Fabricated
in the 65nm CMOS process, the prototype can operate with a supply ranging from 0.85V
to 1.1V, and it achieves a supply sensitivity of 0.034oC/mV and an inaccuracy of ±0.9oC
and ±2.3oC from 0-100oC after 2-point calibration, with and without static nonlinearity
correction, respectively. It achieves a resolution of 0.3oC, resolution FoM of 0.3(nJ/conv)res2 ,
and measurement (conversion) time of 6.5μs
A 5 Gb/s Transmitter With a TDR-Based Self-Calibration of Preemphasis Strength
This brief presents a differentially terminated CML transmitter with a self-calibration scheme based on time-domain reflectometry for preemphasis strength control. Without any handshaking or receiver mode control, the transmitter measures the time of flight by applying the same step input on the two transmission lines of the differential link. Since the receiver does not change its configuration, the proposed scheme greatly simplifies the preemphasis adaptation. To verify the calibration scheme, the proposed transmitter is fabricated in a 0.18-mu m CMOS. For various lengths of the microstrip line on the printed circuit board up to 80 cm, the tested transmitter greatly improves signal integrity and shows clear eye diagrams at 5 Gb/s.X1122sciescopu
Control, Readout and Commissioning of the Ultra-High Speed 1 Megapixel DSSC X-Ray Camera for the European XFEL
The goal of this thesis was to develop the software and firmware basis to control and
read out the 1-Megapixel DEPFET Sensor with Signal Compression (DSSC) detector,
which is being built for the European XFEL (EuXFEL). The DSSC detector proposes
single photon resolution at 0.5 keV photon energy, high dynamic range of 10000
photons at a very high frame rate of 4.5 MHz.
During this thesis, the readout chain has been implemented, which receives the average
data rate of 134 GBit/s from the detector and transfers sorted image data via four
QSFP+ fiber cables to the DAQ system. Additional control software and firmware has
been developed for commissioning of the first 1/16th megapixel prototypes. A multifunctional
measurement and data analysis framework has been created which is used
for characterization of the detector, particularly of properties of the complex readout
ASICs. Additional parameter trimming routines to automatically adapt gain and offset
parameters of a large pixel matrix have been developed in order to generate suitable
configurations which have been applied during two measurement campaigns at the Petra
III synchrotron. For integration into the new Karabo framework, which is provided
by XFEL for beamline control, several software devices have been implemented
Abstracts on Radio Direction Finding (1899 - 1995)
The files on this record represent the various databases that originally composed the CD-ROM issue of "Abstracts on Radio Direction Finding" database, which is now part of the Dudley Knox Library's Abstracts and Selected Full Text Documents on Radio Direction Finding (1899 - 1995) Collection. (See Calhoun record https://calhoun.nps.edu/handle/10945/57364 for further information on this collection and the bibliography).
Due to issues of technological obsolescence preventing current and future audiences from accessing the bibliography, DKL exported and converted into the three files on this record the various databases contained in the CD-ROM.
The contents of these files are:
1) RDFA_CompleteBibliography_xls.zip [RDFA_CompleteBibliography.xls: Metadata for the complete bibliography, in Excel 97-2003 Workbook format; RDFA_Glossary.xls: Glossary of terms, in Excel 97-2003 Workbookformat; RDFA_Biographies.xls: Biographies of leading figures, in Excel 97-2003 Workbook format];
2) RDFA_CompleteBibliography_csv.zip [RDFA_CompleteBibliography.TXT: Metadata for the complete bibliography, in CSV format; RDFA_Glossary.TXT: Glossary of terms, in CSV format; RDFA_Biographies.TXT: Biographies of leading figures, in CSV format];
3) RDFA_CompleteBibliography.pdf: A human readable display of the bibliographic data, as a means of double-checking any possible deviations due to conversion
NASA compendium of satellite communications programs
A comprehensive review is given of worldwide satellite communication programs that range in time from the inception of satellite communications to mid-1974. Particular emphasis is placed on program results, including experiments conducted, communications system operational performance, and technology employed. The background for understanding these results is established through brief summaries of the program organization, system configuration, and satellite and ground terminal characteristics. Major consideration is given to the communications system aspects of each program, but general spacecraft technology and other experiments conducted as part of the same program are mentioned summarily