LowNoiseVco - aLIGO
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Low Noise Voltage-Controlled Oscillator
Description
The current baseline is to use the existing VCO ( D980401-B) to drive the AOM of
the PSL frequency actuator. This AOM runs at a nominal frequency of 80 MHz and
has a total range of 10 MHz. The constant noise level corresponds to a frequency noise
of approximately 10 mHz/rtHz.
A lower noise VCO can be built by reducing the tuning range. We are looking at a
similar design but follow it by a frequency difference divider. A frequency difference
divider takes an input signal divides it down and adds it to a fixed frequency low noise
reference. If the input signal experiences a high phase noise, the phase noise in the
output signal is reduced by the divider ratio---assuming all other noise sources are
negligible. A second stage using another frequency difference divider can be added to
yield even lower phase noise---albeit by giving up another factor of 10 in range. This
is too small for the PSL but might be useful for locking the arm cavities using green
light.
Specifications
Frequency:
• 71 MHz (reference input)
• 79-81 MHz nominal (output)
• 2 MHz full range (output)
Input (tuning):
• +/-20V differential
• 1.6 Hz/40 Hz pole/zero pair
• 2-pin LEMO
Oscillator output:
• 13 dBm
• N female
• 131.25 MHz nominal
Frequency divider input:
•
•
•
•
13 dBm
N female
131.25 MHz nominal (first stage)
80 MHz nominal (second stage)
Frequency divider output:
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LowNoiseVco - aLIGO
•
•
•
•
•
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13 dBm
N female (2x)
80 MHz nominal
2 MHz full range (first stage)
200 kHz full range (second stage)
Reference input:
• 13 dBm
• N female
• 71 MHz nominal
Phase noise (reference input):
Frequency
Phase noise spec
10 Hz
-90 dBc/Hz
100 Hz
-110 dBc/Hz
1 kHz
-140 dBc/Hz
10 kHz
-160 dBc/Hz
100 kHz
-165 dBc/Hz
Phase noise from model (output):
Phase noise spec
Frequency
First stage
Second stage
10 Hz
-60 dBc/Hz
-80 dBc/Hz
100 Hz
-97 dBc/Hz
-112 dBc/Hz
1 kHz
-128 dBc/Hz
-137 dBc/Hz
10 kHz
-152 dBc/Hz
-157 dBc/Hz
100 kHz
-162 dBc/Hz
-162 dBc/Hz
Amplitude noise (input & output):
Frequency
AM noise spec
10 Hz
-140 dBc/Hz
100 Hz
-150 dBc/Hz
1 kHz
-150 dBc/Hz
10 kHz
-150 dBc/Hz
Physical:
• 19" rack mount
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• 2U
Power:
• +/-16.5V and +/-24V
Modeling and Characterization
Circuit model
T0900138-v1
Circuit model files
T0900138-v1
Characterization
T0900451-v1
Phase Noise Plot
SSB Noise*
(*) The noise of the OCXO and the second stage VCO have additional uncertainties
below 100Hz due to approximate loop suppression correction.
Modules
Device
Manufacturer
Model
Link
VCO
Synergy Microwave
MFC91119-10
RF Amplifier
Wenzel Associates
TBD
[]
Divider 1:16
Wenzel Associates
TBD
[]
Divider 1:10
Wenzel Associates
TBD
[]
Mixer
Wenzel Associates
TBD
[]
Filter
Lark Engineering
MC80-80-4AA
[]
T1000512-v1
Drawings
Assembly
Description
Revision
pdf
files
Assembly schematics
A
D0900605-A
zip
Enclosure
1
D0900142-v1
dwg
Front panels
A
D0900606-A
fpd
Rear panels
B
D0900607-B
fpd
Mounting plate
A
D0900608-A
fpd
Test Procedure
TBD
Boards
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Description
Revision
Low Noise VCO Oscillator Source
Schematics
A
Low Noise VCO Panel Schematics
A
Interface Board Schematics
A
Low Noise Power Board
pdf
files
D0900609A
zip
D0900629-
A
zip
D1000064-
A
zip
Low Noise Power Module
Test Rig
Description
Revision
pdf
files
VCO tester
1
D1100545-v1
zip
VCO tester front panel
1
D1100571-v1
fpd
VCO tester rear panel
1
D1100572-v2
fpd
Images
Front
Top
Front above
aLIGO: LowNoiseVco (last edited 2011-04-01 21:21:31 by DanielSigg)
https://awiki.ligo-wa.caltech.edu/aLIGO/LowNoiseVco?action=print
4/21/2011