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Proceedings ArticleDOI

A 96 channel receiver for the ILCTA LLRF system at fermilab

U. Mavric, Brian Chase, J. Branlard, E. Cullerton, Daniel Klepec1 
25 Jun 2007-pp 2271-2273

AbstractThe 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.

Topics: Cryomodule (56%), Power dividers and directional couplers (53%), Amplifier (51%), Waveguide filter (51%), Chassis (51%)

Summary (2 min read)

Introduction

  • Station has 26 nine cell cavities driven from one klystron.
  • A down-converter chassis is being developed that contains 12 eight channel analog modules and a single upconverter 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 final performance of the receiver is defined by many phenomena, which makes the error identification problem more complex.

Functional Block Diagram of the Receiver

  • The size of the board and consequently the number of channels per board was chosen to facilitate the mechanical design and mounting of multiple boards in the rack.
  • The space between two adjacent RF inputs will be 1.5 inches.
  • Besides eight RF 1.3GHz input channels, the receiver board will have 16 down converted IF (13MHz) output ports, 1 input LO (1.313GHz) port and various others I/O ports as shown in Figure 1.
  • The authors also plan to mount fault cable detectors and LO power monitors.
  • ANALYSIS OF MAIN PARAMETERS IN THE RECEIVER.

Broad-band Noise Figure

  • The overall noise figure of one channel is calculated according to the noise figure values given in datasheets.
  • *Work supported by Fermi Research Alliance LLC.
  • The relative noise floor is consequently - 157dBc/Hz.
  • If lower-broad band noise specifications are to be met, a higher input signal and a more linear mixer can be used.

Narrow-band Noise Figure

  • The major phase noise contributor in the LO distribution part of the receiver is the LO amplifier.
  • Input power to the LO amplifier and the nonlinearity of the amplifier define the amount of the induced flicker noise.
  • The measurement method used for measurements presented in Figure 3 is known as single oscillator phase noise measurement technique according to literature [5].
  • Lower LO power decreases linearity, which is investigated in the following section.
  • The integrated phase noise for various mixers is given in Table 1.

Nonlinearities

  • A lower level mixer is usually less linear than a higher level mixer.
  • Measurements of mixers presented in Figure 3 would show that there is approximately 20dB difference between the power in the second and the third harmonic for the level 7 and the level 17 mixers.
  • Measurements show that level 13 and level 10 mixers exhibit very similar linearity performance, which favorizes the level 10 mixer.
  • A perturbation analysis with the 8 channel receiver and 8 superconducting RF cavities was carried out.
  • Analysis shows that the receiver should operate in the compression point region between 0.01dB and 0.1dB if less than 0.1% of gradient deviation wants to be achieved.

Cross-Talk between RF Channels

  • In order to minimize cross-talk between channels special attention has to be paid to cables, layout, chassis design and matching of components.
  • The IF cables connecting the receiver chassis and the MFC digital board are manufactured by Harting and measurements show that isolation between adjacent channels is better than 80dB.
  • One of the most critical parts in terms of matching and isolation is the mixer.
  • There are various paths through the mixer that cause the RF or IF signal to couple in the adjacent channel.
  • Besides matching and cables, proper layout and chassis construction is also an important way of coupling reduction.

Temperature Stability of the Receiver

  • A receiver has been built on an aluminium plate with heaters and temperature sensors regulated by a temperature controller.
  • Temperature excursions of 2°C on the aluminium plate were induced and a phase fluctuation that equals to 0.25° was measured.
  • Using a more sophisticated temperature controller (PID) would decrease large temperature excursions and consequently decrease phase deviation swings.

One Channel Layout

  • The specific parts that are planned to be used for the 8 channel receiver board are shown in Figure 2.
  • The final choice of IF amplifier has not yet benn made.
  • Analog Devices and other manufacturers offer a broad spectrum of ultra low noise variable gain amplifiers.
  • They are designed to drive high impedance loads (> 500Ω), which causes additional power losses in impedance transformers.
  • At higher gains the nonlinearity becomes a serious issue.

Eight Channel Layout

  • Figure 4 shows a design of the bottom and top layer of the board.
  • The input down-converter modules will be enclosed in a aluminium cage.
  • Varghese P., Barnes B., Branlard J., Chase B., W Joireman P., Klepec D., Mavric U., Tupikov V., “Multichannel Vector Field Control Module for LLRF Control of Superconducting Cavities”, This Conference – WEPMN112 [2].
  • Walls F.L. and Stein S.R., “Accurate Measurements of Spectral Density of Phase Noise in Devices”, National Bureau of Standards [4].

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A 96 CHANNEL RECEIVER FOR THE ILCTA LLRF SYSTEM AT
FERMILAB
*
Uros Mavric
#
, Brian Chase, Julien Branlard, Ed Cullerton, Dan Klepec
Fermi National Accelerator Laboratory, Batavia, IL, USA.
Abstract
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 1.3GHz,
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 cross-
talk issues, special attention is given to these parts in the
design of the LO port multiplication and distribution.
INTRODUCTION
Identifying the main error contributors in the LLRF
electronics is important for error minimization. The final
performance of the receiver is defined by many
phenomena, which makes the error identification problem
more complex. Usually a combination of computer
simulations and prototype on-the-bench testing usually
helps to understand the major pitfalls. A Matlab based
model has been developed to study the impact of the
receiver parameters on the control of multiple cavities.
Functional Block Diagram of the Receiver
The 96 channels receiver will be organized in 8
channels per board, which requires 12 boards. The size of
the board and consequently the number of channels per
board was chosen to facilitate the mechanical design and
mounting of multiple boards in the rack. The space
between two adjacent RF inputs will be 1.5 inches.
Besides eight RF 1.3GHz input channels, the receiver
board will have 16 down converted IF (13MHz) output
ports, 1 input LO (1.313GHz) port and various others I/O
ports as shown in Figure 1. One receiver board will be
equipped with temperature sensors and various testing
points in order to facilitate the debugging of the bard or to
inject signals in the operational conditions (for instance
dithering). We also plan to mount fault cable detectors
and LO power monitors.
ANALYSIS OF MAIN PARAMETERS IN
THE RECEIVER
Broad-band Noise Figure
Broad-band noise is assumed to be dominated by
amplitude noise. The overall noise figure of one channel
Figure 1: Block diagram of input and output ports of the
receiver.
is calculated according to the noise figure values given in
datasheets. Figure 2 shows the schematic of one channel
and absolute noise power levels at some test points along
the processing chain.
Figure 2: Schematic of one channel. Noise power levels,
signal power levels and nonlinearities are shown.
___________________________________________
*Work supported by Fermi Research Alliance LLC. Under DE-AC02-
07CH11359 with the U.S. DOE
#
mavric@fnal.gov
FERMILAB-CONF-07-299-AD

According to these calculations we expect to achieve
app. -152dBm/Hz of noise power at the output, which is
equivalent to 36dB of input noise figure. The output
power level is app. +5dBm, to match the Multi-channel
Field Control module (MFC) [1] input power
requirements. The relative noise floor is consequently -
157dBc/Hz. This is much lower than a -148dBc/Hz noise
floor of the 12bit ADC on the MFC board and is about the
same as a 14bit part. It is supposed that the noise figure of
the mixer is app. 1dB higher than its insertion loss (see
literature [2]) and that we managed to suppress all the
mixing products by proper matching. Broad-band
amplitude noise introduced by the LO is supposed not to
affect the overall noise floor since the LO amplifiers are
driven in saturation and the LO signal is filtered. The
main limiting component for the schematic in Figure 2, in
terms of broad-band noise floor, is the IF amplifier. If
lower-broad band noise specifications are to be met, a
higher input signal and a more linear mixer can be used.
In this case the IF amplifier can have lower gain.
However, higher mixer linearity is usually associated with
higher LO port power, which means that the LO amplifier
has to be higher gain. This contributes to a higher close in
phase noise as presented in the following paragraph. The
design presented in Figure 2 is a compromise between
linearity, broad-band noise, close in phase noise and LO
input power.
Table 1: Equivalent time rms jitter and phase rms
deviation for some mixers presented in Figure 3.
(Integration bandwidth 100Hz to 500kHz)
Mixer
t
jrms
[fs] φ
jrms
[°]
HMC483MS8G (Active)
2.4 1.1e-3
SYM25DLHW (L10)
1.6 7.8e-4
ZFM-2000 (L7)
1.8 8.6e-4
SYM25DHW(L17)
1.4 6.7e-4
Narrow-band Noise Figure
Narrow-band noise figure of the receiver is assumed to
be defined only by phase noise. Phase noise introduced in
the LO distribution of the receiver is translated to the IF
port and it is defined by the slope of the mixer (V/rad)
(for more details see [3]). The major phase noise
contributor in the LO distribution part of the receiver is
the LO amplifier. The phase noise issues of a microwave
amplifier are thoroughly studied in literature [4]. Input
power to the LO amplifier and the nonlinearity of the
amplifier define the amount of the induced flicker noise.
The flicker noise is up-converted to the carrier, which is
transmitted through mixing on the IF port and therefore to
the whole system. Figure 3 shows an example of the
amount of phase noise generated by an MMIC amplifier
(HMC481MP86, www.hittie.com). The measurement
method used for measurements presented in Figure 3 is
known as single oscillator phase noise measurement
technique according to literature [5]. The results in
Figure 3 show that in the case of these particular mixers it
is better to use a passive mixer with an external LO
amplifier. It also shows that we do not need to drive a
higher level mixer to get the best phase noise
performances. However, lower LO power decreases
linearity, which is investigated in the following section.
The integrated phase noise for various mixers is given in
Table 1. The measurement method used for
measurements presented in Figure 3 is known as single
oscillator phase noise measurement technique according
to literature [5]. The integrated phase noise for various
mixers is given in Table 1.
10
1
10
2
10
3
10
4
10
5
-165
-160
-155
-150
-145
-140
-135
-130
-125
-120
-115
Freque ncy [Hz]
Noise Level [dBc/Hz]
HMC483MS8G (LO=0dBm, RF=+7dBm)
ZFM-2000 (LO=+7dBm, RF=+7dBm)
SYM-25DLHW (LO=+10dBm RF=+7dBm) Amp In Front of the Splitter
SYM-25DLHW (LO=+10dBm RF=+7dBm)
SYM-25DHW (LO=+17dBm RF=+7dBm)
SYM-25DMHW (LO=+13dBm RF=+7dBm)
SYM-2000 (LO=+7dBm RF=+7dBm)
LNA Noise Floor
(-171dBm/Hz)
Amplified AM Noise Floor From the Source
-137dBm/Hz(L7)
-145dBm/Hz (L17)
-148dBm/Hz (L10)
-124dBm/Hz (Active)
-155dBm/Hz
-144dBm/Hz(L13)
Figure 3: Close in phase noise measurements for mixer
and LO amplifier combination.
Nonlinearities
A lower level mixer is usually less linear than a higher
level mixer. Measurements of mixers presented in Figure
3 would show that there is approximately 20dB difference
between the power in the second and the third harmonic
for the level 7 and the level 17 mixers. Measurements
show that level 13 and level 10 mixers exhibit very
similar linearity performance, which favorizes the level
10 mixer. Comparison of a level 10 mixer and level 17
mixer shows that the second and the third harmonic differ
for approximately 13dB between the two mixers. For the
receiver design we have chosen the level 10 mixer due to
lower LO amplifier gain requirements.
A perturbation analysis with the 8 channel receiver and
8 superconducting RF cavities was carried out. Dispersion
in peak gradients between cavities causes the calibrated
channels in the receiver to work at different points of the
nonlinear curve. Analysis shows that the receiver should
operate in the compression point region between 0.01dB
and 0.1dB if less than 0.1% of gradient deviation wants to
be achieved.
Cross-Talk between RF Channels
In order to minimize cross-talk between channels
special attention has to be paid to cables, layout, chassis
design and matching of components. The IF cables
connecting the receiver chassis and the MFC digital board
are manufactured by Harting and measurements show that
isolation between adjacent channels is better than 80dB.
One of the most critical parts in terms of matching and
isolation is the mixer. There are various paths through the
mixer that cause the RF or IF signal to couple in the
adjacent channel. Measurements show that there is a

difference of more than 10dB between a poorly matched
mixer and a mixer with an improved match. Besides
matching and cables, proper layout and chassis
construction (shielding) is also an important way of
coupling reduction.
Temperature Stability of the Receiver
A receiver has been built on an aluminium plate with
heaters and temperature sensors regulated by a
temperature controller. Temperature excursions of 2°C on
the aluminium plate were induced and a phase fluctuation
that equals to 0.25° was measured. Using a more
sophisticated temperature controller (PID) would decrease
large temperature excursions and consequently decrease
phase deviation swings.
IMPLEMENTATION OF THE 8
CHANNEL RECEIVER
One Channel Layout
The specific parts that are planned to be used for the 8
channel receiver board are shown in Figure 2. The final
choice of IF amplifier has not yet benn made. Analog
Devices and other manufacturers offer a broad spectrum
of ultra low noise variable gain amplifiers. However, they
are designed to drive high impedance loads (> 500),
which causes additional power losses in impedance
transformers. At higher gains the nonlinearity becomes a
serious issue. Monolithic microwave integrated circuit
amplifier modules are easier to use but tend to be more
nonlinear and are usually meant to be used at higher
frequencies.
Eight Channel Layout
Figure 4 shows a design of the bottom and top layer of
the board. Each board will be 8U (14 inches) high. The
input down-converter modules will be enclosed in a
aluminium cage. Isolation between LO branches will be
reinforced by ground fences and proper line routing.
Figure 4: A top and bottom view of the eight channel
receiver board.
Each of 12 8-channel boards will be placed on the top
of the rack in a crate. The crate will be slightly tilted so
that the rigid cables will not need to be additionally
banded before coming to the receiver board.
MEASUREMENT RESULTS OF THE
PROTOTYPE
According to the schematic in Figure 1, a two channel
prototype was constructed. Before acquisition, the two
13MHz signals were phase shifted in order to be in
quadrature. The acquired digital data was multiplied and
filtered with a 500 kHz low-pass FIR filter. This gives the
residual phase noise of the receiver and MFC board. Any
common phase deviation of the source generator is
subtracted by the method. Standard deviation of the
filtered signal is 3e-3° at 500 kHz SSB bandwidth.
On the IF port of the prototype we measured the second
and the third harmonics produced by the mixer, which
were 40dB high and the isolation between these two
channels was approximately 88dB with proper matching
on the mixer ports.
CONCLUSIONS
In the paper we discussed the main parameters that
have to be considered for proper operation of the receiver.
A target value for broad-band noise at the output of the
receiver is -157dBc/Hz, the integrated close in phase
noise over at 500 kHz bandwidth should be better than
3e-3°, the receiver should operate between 0.01dB and
0.1dB compression point and cross-talk measurements
show that we can achieve better than 80dB of isolation. A
per se part of the project is the implementation where
mechanics of the chassis, ease of module access and
diagnostics have to be considered. At present we are in
the phase of 8 channel board layout and two channel
prototype testing.
REFERENCES
[1] Varghese P., Barnes B., Branlard J., Chase B., W
Joireman P., Klepec D., Mavric U., Tupikov V.,
“Multichannel Vector Field Control Module for
LLRF Control of Superconducting Cavities”, This
Conference – WEPMN112
[2] A. Mass S. , “Microwave Mixers – Second Edition”,
Artech House, Inc. 1993
[3] Walls F.L. and Stein S.R., “Accurate Measurements
of Spectral Density of Phase Noise in Devices”,
National Bureau of Standards
[4] Hati A., Howe D.A., Walls L.F., Walker
D.K.,“Merits of PM Noise Measurements over Noise
Figure: A Study at Microwave Frequencies”, IEEE
Transactions on Ultrasonics, Ferroelectrics and
Frequency Control, vol.53, No.10, October 2006
[5] “Infrared and Millimeter Waves”, Vol.11, pp.239-
289, 1984
Citations
More filters

Journal ArticleDOI
TL;DR: This paper presents 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.
Abstract: 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.

10 citations


Cites background from "A 96 channel receiver for the ILCTA..."

  • ...The two printed circuit boards are the eight channel analog receiver board [6] (on the left) and...

    [...]


Proceedings ArticleDOI
25 Jun 2007
TL;DR: The MFC (Multichannel Field Control) module is a 33- channel, FPGA based down-conversion and signal processing board in a single VXI slot, with 4 channels of high speed DAC outputs, which provides additional computational and control capability for calibration and implementation of more complex control algorithms.
Abstract: The field control of multiple superconducting RF cavities with a single Klystron, such as the proposed RF scheme for the ILC, requires high density (number of RF channels) signal processing hardware so that vector control may be implemented with minimum group delay. The MFC (Multichannel Field Control) module is a 33- channel, FPGA based down-conversion and signal processing board in a single VXI slot, with 4 channels of high speed DAC outputs. A 32-bit, 400MHz floating point DSP provides additional computational and control capability for calibration and implementation of more complex control algorithms. Multiple high speed serial transceivers on the front panel and the backplane bus allow a flexible architecture for inter-module real time data exchanges. An interface CPLD supports the VXI bus protocol for communication to a SlotO CPU, with Ethernet connections for remote in system programming of the FPGA and DSP as well as data acquisition.

10 citations


Cites methods from "A 96 channel receiver for the ILCTA..."

  • ...Thirty channels of IF inputs are transformer coupled to 4 , 8-ch, 12-bit, 65 MHz ADCs with a voltage gain of 2, through an impedance matching filter network[2]....

    [...]


J. Branlard1, B.Chase, E.Cullerton, P.W. Joireman, V. Tupikov 
01 Sep 2010
Abstract: The High Intensity Neutrino Source (HINS) R&D program requires super conducting single spoke resonators operating at 325 MHz (SSR1) [1]. After coupler installation, these cavities are tested at the HINS-SRF facility at Fermilab. The LLRF requirements for these tests include support for continuous wave and pulsed mode operations, with the ability to track the resonance frequency of the tested cavity. Real-time measurement of the cavity loaded Q and Q0 are implemented using gradient decay techniques, allowing for Q0 versus Eacc plots. A real time cavity simulator was also developed to test the LLRF system and verify its functionality. LLRF SYSTEM OVERVIEW The LLRF system is depicted in Fig. 1. The 325 MHz RF reference is provided by a signal generator (Aeroflex IFR 2023A), for tunability. The master oscillator and local oscillator chassis distributes the 325 MHz reference signal and generates the 338 MHz LO. The LO is obtained by mixing the 325 MHz RF signal with a 13 MHz intermediate frequency (IF), internally generated by dividing the 325 MHz reference by 25. This allows the LO to track the RF signal when it is tuned to match the cavity resonance frequency.

7 citations


Cites background from "A 96 channel receiver for the ILCTA..."

  • ...The 8 channel receiver / 1 channel transmitter [2] previously developed for Fermilab 1....

    [...]


Journal ArticleDOI
Abstract: Low-level radio frequency (LLRF) systems stabilize the electromagnetic field in the RF cavities used for beam acceleration in particle accelerators. Reliable, accurate, and precise detection of RF amplitude and phase is particularly important to achieve high field stability for pulsed accelerators of free-electron lasers (FEL). The digital LLRF systems employ analog-to-digital converters to sample the frequency down-converted RF signal and use digital demodulation algorithms to calculate the RF amplitude and phase. Different sampling strategies and demodulation algorithms have been developed for these purposes and are introduced in this paper. This article focuses on advanced topics concerning RF detection, including accurate RF transient measurement, wideband RF detection, and RF detection with an asynchronous trigger, local oscillator, or clock. The analysis is based on the SwissFEL measurements, but the algorithms introduced are general for RF signal detection in particle accelerators.

6 citations


Proceedings ArticleDOI
J. Branlard, S. Simrock, S. Michizono1
25 Jun 2007
Abstract: The key to a successful LLRF design for the International Linear Collider (ILC) relies on a combined effort from the different laboratories involved in this global project. This paper covers the ILC LLRF design progress both long term and for current test facilities around the world. The SIMCON controller board, originally developed at DESY has been successfully used at FNAL to control superconducting capture cavity I and II. LLRF team leaders from DESY, KEK and FNAL have worked together toward a common design and costing estimate for the ILC LLRF. This paper gives a general overview of the LLRF development achieved through continuous collaboration and communication between the various labs involved in the ILC LLRF design process.

5 citations


References
More filters

Book
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820 citations


Journal ArticleDOI
TL;DR: This paper primarily addresses the usefulness of phase-modulation noise measurements versus noise figure (NF) measurements in characterizing the merit of an amplifier, and concludes that, although NF is sometimes used as a selection criteria for an amplifier for low-level signal, NF yields no information about potentially important close-to-carrier 1/f noise of an amplifier nor broadband noise in the presence of a high- level signal.
Abstract: This paper primarily addresses the usefulness of phase-modulation (PM) noise measurements versus noise figure (NF) measurements in characterizing the merit of an amplifier. The residual broadband (white PM) noise is used as the basis for estimating the NF of an amplifier. We have observed experimentally that many amplifiers show an increase in the broadband noise of 1 to 5 dB as the signal level through the amplifier increases. This effect is linked to input power through the amplifier's nonlinear intermodulation distortion. Consequently, this effect is reduced as linearity is increased. We further conclude that, although NF is sometimes used as a selection criteria for an amplifier for low-level signal, NF yields no information about potentially important close-to-carrier 1/f noise of an amplifier nor broadband noise in the presence of a high-level signal, but a PM noise measurements does. We also have verified experimentally that the single-sideband PM noise floor of an amplifier due to thermal noise is -177 dBc/Hz, relative to a carrier input power of 0 dBm

32 citations


Proceedings ArticleDOI
01 Jun 1977
Abstract: Systematic errors larger than 10 dB can occur in the measurement of the spectral density of phase unless considerable caution is exercised. Some potential problems due to the shape of the analyzer passband and the Fourier frequency dependence of mixers are discussed. Three measurement systems are analyzed to determine the conditions under which they may be used to make spectral density measurements with an accuracy of 0.2 dB.

14 citations


Proceedings ArticleDOI
25 Jun 2007
TL;DR: The MFC (Multichannel Field Control) module is a 33- channel, FPGA based down-conversion and signal processing board in a single VXI slot, with 4 channels of high speed DAC outputs, which provides additional computational and control capability for calibration and implementation of more complex control algorithms.
Abstract: The field control of multiple superconducting RF cavities with a single Klystron, such as the proposed RF scheme for the ILC, requires high density (number of RF channels) signal processing hardware so that vector control may be implemented with minimum group delay. The MFC (Multichannel Field Control) module is a 33- channel, FPGA based down-conversion and signal processing board in a single VXI slot, with 4 channels of high speed DAC outputs. A 32-bit, 400MHz floating point DSP provides additional computational and control capability for calibration and implementation of more complex control algorithms. Multiple high speed serial transceivers on the front panel and the backplane bus allow a flexible architecture for inter-module real time data exchanges. An interface CPLD supports the VXI bus protocol for communication to a SlotO CPU, with Ethernet connections for remote in system programming of the FPGA and DSP as well as data acquisition.

10 citations


Frequently Asked Questions (1)
Q1. What contributions have the authors mentioned in the paper "A 96 channel receiver for the ilcta llrf system at fermilab" ?

Critical parts of the design for LLRF applications are identified and a detailed description of the circuit with various characteristic measurements is presented.