LIGO Document T0900451-v1

Characterization of a Voltage Controlled Oscillator

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T - Technical notes
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We assemble and test a prototype voltage controlled oscillator (VCO) for use in the pre-stabalized laser (PSL) control system in Advanced LIGO. The prototype will replace current hardware to ensure the VCO does not limit the noise performance of the PSL after Advanced LIGO upgrades. The VCO design requires a nominal frequency output at 80MHz and a range 1MHz combined with low phase noise near -150dBc/Hz at 10kHz carrier offset. These requirements preclude the direct use of commercially avaliable hardware such as VCO modules or crystal oscillators. The VCO design uses a frequency synthesizing approach to achieve required performance. Data gathered in testing include output phase noise, internal voltage noise and transfer functions. These data indicate that the VCO performs as expected and its noise performance is acceptable for Advanced LIGO.
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This is a SURF report.
PhaseNoiseSSB: The noise of the OCXO and the second stage VCO have additional uncertainties below 100Hz due to approximate loop suppression correction.
The VCO FDD SSB measurements at frequencies below 100Hz were added on 4/16/2014 (see LHO alog 11385).
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