This article describes a radio frequency (RF) interconnection for the micro telecommunication computing architecture (MTCA) open standard published by the PCI Industrial Computer Manufacturers Group. ...The interconnection is capable of transmitting signals with frequencies ranging from dc to 3 GHz from the rear transmission module (RTM) to the advanced mezzanine card (AMC, IEEE1386.1). The existing connection is based on differential connectors and suffers from strong crosstalk between the pairs. The main motivation behind our research is to develop a new connection with high isolation between the ports that can transmit RF signals up to 3 GHz. A new MTCA.4 interconnection class RF1.0 based on two improved single-ended multiport coaxial connectors with up to 12 contacts is introduced. This could open a new field of MTCA-based modular high-frequency instrumentation, e.g., for beam diagnostics in particle accelerators, RF preconditioning in radar systems, or in 5G telecom wireless networks. A sophisticated through-hole technology (THT) and surface-mounted device (SMD) footprint pattern with very-low crosstalk, down to −90 dB between the connector pins, is presented. The new broadband connection between the AMC and the RTM allows the use of modern direct-sampling digitizers analog-to-digital converter (ADC) and fast digital-to-analog converters (DACs) on MTCA.4 AMCs, while maintaining the high spectral purity of the converters. This allows omitting large mixer circuits on the RTM, which were needed to reduce the signal frequency due to insufficient isolation of the current differential Zone 3 connector. The RF1.0 interconnection class presented in this article could enable a highly modular instrumentation platform for processing of RF signals.
Analog cavity simulator Orel, Peter; Mavrič, Uroš
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2013, Letnik:
729
Journal Article
Recenzirano
Most of the low-level radio frequency (LLRF) systems are being developed well before the machines are being set up and ready to be commissioned. Therefore it is imperative to be able to test and ...evaluate their functionality and performance in the laboratory, before the instrument is installed in the final configuration. Real accelerator cavities are very expensive and frequency-dependent, hence impractical for mass factory testing of instrumentation. As an alternative, we developed an analog cavity simulator. The article gives an explanation of the main design concept, some key considerations of its implementation in order to reach the required specifications, and presents the test results, showing the simulator performance.
•Presentation of a novel approach for the design principle.•Extensive description of key technical features of the design implementation.•Presentation of a cheap and easily manufacturable prototype.•Proof of concept and proof of performance results.•Discussion for further improvement of the design implementation.
Design approaches for the X band LLRF system Mavric, Uros; Jug, Gasper
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2011, Letnik:
657, Številka:
1
Journal Article
Recenzirano
The low-level RF (LLRF) system regulates disturbances over a limited bandwidth in accordance with its capabilities and the RF loop parameters. The disturbances usually originate in the RF system or ...can be coupled to the RF system from the environment. In this paper a general overview of the possible design approaches for a digital LLRF system operating in X band is presented. Firstly, the possible design approaches of the RF front/back ends are presented and reviewed. We also define the main design parameters for the RF front/back ends. Parameters like isolation between channels, noise, gain, linearity and number of IF stages are put into the perspective of machines using RF components in the X band. An important part of the LLRF system is the local RF timing generation and distribution, which is also treated in the paper. In the second part of the paper the main design approaches in the digital signal processing part of the LLRF system are presented. The emphasis is on the algorithms that are machine specific. Some standard processing algorithms like adaptive feed-forward and arbitrary shaping of feed-forward pulses are presented. Finally, a suggestion for the X band LLRF design is given.
This article summarizes theoretical and technical limitations when applying carrier-suppression interferometer (CSI) methods for precision phase-noise measurements at attosecond resolution. The CSI ...setup reported here outperforms conventional down-mixing methods by more than two orders of magnitude. For phase noise measurements at 1.3 GHz operation frequency, a detection floor of <inline-formula> <tex-math notation="LaTeX">\mathscr {L}={-205}\,\,{\text {dBc/Hz}} </tex-math></inline-formula> and an excellent time resolution of 10.76 as within an offset frequency range from 40 Hz to 1 MHz have been achieved without the usage of cross correlation or power recycling techniques. Measurement setup resolution limits, calibration methods, and effects of transmission line group delays are reported. Phase shifters and attenuators in the CSI were identified as key components. Different phase shifter technologies based on passive switches, varactor diodes, and capacitors were investigated. The presented research can be used in future in combination with conventional receiver techniques and enhances the state of the art of phase noise measurements to attosecond resolution and above.
The proposed RF distribution scheme for the two 15
km long ILC LINACs uses one klystron to feed 26 superconducting RF cavities operating at 1.3
GHz. For a precise control of the vector sum of the ...signals coming from the SC cavities, the control system needs a high-performance, low-cost, reliable and modular multichannel receiver. At Fermilab we developed a 96-channel, 1.3
GHz analog/digital receiver for the ILC LINAC LLRF control system. In this paper we present a balanced design approach to the specifications of each receiver section, the design choices made to fulfill the goals and a description of the prototyped system. The design is tested by measuring standard performance parameters, such as noise figure, linearity and temperature sensitivity. Measurements show that the design meets the specifications and it is comparable to other similar systems developed at other laboratories, in terms of performance.
The main advantages of the implemented innovative RF design are reproducibility, accuracy, low measurement uncertainty, and compact design. They were achieved by implementing the direct RF sampling ...and the completely new, patent pending technological approach of quasi-crossbar multiplexing and associated measurement method. The innovative quasi-crossbar switch matrix unites the benefits of both the multi-channel and the multiplexed system and at the same time compensates the disadvantages of the two. We achieve reproducibility and good 'beam vs. current' dependence, which are multiplexed system characteristics and, using a multi-channel approach, we ensure a broader band of operation.
The present configuration of an ILC main LINAC RF station has 26 nine cell cavities driven from one klystron. With the addition of waveguide power coupler monitors, 96 RF signals will be ...down-converted and processed. A down-converter chassis is being developed that contains 12 eight-channel analog modules and a single up- converter module. This chassis will first be deployed for testing a cryomodule composed of eight cavities located at New Muon Laboratory (NML) - Fermilab. Critical parts of the design for LLRF applications are identified and a detailed description of the circuit with various characteristic measurements is presented. The board is composed of an input band-pass filter centered at 1.3 GHz, followed by a mixer, which down-converts the cavity probe signal to a proposed 13 MHz intermediate frequency. Cables with 8 channels per connector and good isolation between channels are being used to interconnect each down-converter module with a digital board. As mixers, amplifiers and power splitters are the most sensitive parts for noise, nonlinearities and crosstalk issues, special attention is given to these parts in the design of the LO port multiplication and distribution.
Using the measuring technique described in the previous section, measurements using 7, 13, 10 and 17 dBm level mixers were carried out. The MMIC amplifier (HMC481 from Hittite)11 in the LO branch was ...the same in all cases (except for the measurement with the active mixer). By varying the attenuation at the output of the amplifier, various power levels were achieved that were needed for each particular mixer. Figure 4 shows the relative noise floor of phase noise measurement results in dBc/Hz.
RTM RF Backplane for MicroTCA.4 crates Czuba, Krzysztof; Jezynski, Tomasz; Lesniak, Tomasz ...
2014 19th IEEE-NPSS Real Time Conference
Conference Proceeding
We developed a new Rear Transition Module (RTM) Backplane for MicroTCA.4 crates that is compliant with the PICMG standard and is an optional crate extension. The RTM Backplane provides multiple links ...for high-precision clock and RF signals to analog μRTM cards. Usage of an RTM Backplane allows to significantly simplify the cable management, and therefore to increase the reliability of electronic controls when multiple analog RF front-ends are required. In addition, the RTM backplane allows also to add so called extended RTM (eRTM) and RTM Power Modules (RTM-PM) to a 12-slot MicroTCA crate. Up to four 6 HP wide eRTMs and two RTM-PMs can be installed behind the front PM and MCH modules. An eRTM attached to the MCH via Zone 3 connector is used for analog signal management on the RTM backplane. This eRTM allows also installing a powerful CPU to extend the processing capacity of the MTCA.4 crate. Remaining three eRTMs provide additional space for analog and digital electronics that may not fit on the standard RTM cards. The RTM-PMs deliver managed low-noise (separated from front crate PMs) analog bipolar power (+VV, -VV) for the μRTMs and an unipolar power for the eRTMs. This extends functionality of the MicroTCA.4 crate and offers unique performance improvement for analog front-end electronics. This paper covers a new concept of the RTM Backplane, a new implementation for the real-time LLRF control system and performance evaluation of designed prototype.
This paper presents novel pickup geometries having planar transmission lines for beam position monitoring in the Free Electron Laser at DESY (FLASH). The sensor is designed for a rectangular beam ...pipe with flange mounted pickup structures within a magnetic chicane that allows to determine the beam position as well as the energy of the beam. The necessary measurement resolution within the lower micrometer range requires signal reflections less than -25 dB at the operation frequency of 3 GHz. Measurement results of a realized pickup with standard coax- to microstrip transitions exhibit moderate reflection coefficients. Simulations of two new microstrip and grounded CPW pickup structures with optimized perpendicular connector to transmission line transitions show reflection coefficients well inside the specifications. Simulations with a particle beam show reflected signal components with less than 4% of the peak voltage signal which allows a minimum position accuracy better than 20 μm
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