Prsentation PowerPoint

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High spectral purity 26 GHz oscillator based on
a SiO2 Whispering Gallery Mode Resonator
P. Salzenstein, R. Barhaila, Y. Gruson, Y.
Kersalé and V. Giordano
Laboratoire de Physique et de Métrologie des
Oscillateurs (LPMO) du CNRS UPR3203, associé à
lUniversité de Franche-Comté, 32 avenue de
lObservatoire, F25044 Besançon Cedex,
France e-mail patrice.salzenstein_at_lpmo.edu
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Outline

• How to achieve low phase noise microwave
  oscillators at 26GHz?
• Choice of the material for the resonator
• Design of the resonator
• Description of the ocillator 
• Phase noise measurement
• Results and discussion

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EFTF 2002 Russia
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Choice of the material for the resonator

• Leeson model
• One of the key parameter Resonator Q-factor
• Sapphire
• using the same Whispering Gallery Mode Resonator
  (WGMR) technique
• High-Q Quartz resonator
• (high quality cristals, low losses at microwave
  frequencies, low cost)

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Resonator Design (1)
?

• Mode matching method determination of
  resonance frequency

• Theoritical and experimental frequency of the
  WGHm,0,0 Mode

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Resonator Design (2)

• principle

Coupling coefficients have been adjusted by
changing the penetration length of the antenna
into the copper cavity

• quartz disk centered in a gold-plated copper
  cavity

• Two electrical probes fixed on each lid of
  the cavity, used to excite the quasi-TM
  whispering gallery (WGH) mode family of this
  resonator

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EFTF 2002 Russia
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Resonator design (3)
and after packaging
Before
Picture of the 26GHz resonator

• Insertion losses are set to 15 dB
• Loaded Q-factor obtained 23 000

• WGH10,0,0 mode at 26 GHz

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EFTF 2002 Russia
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Oscillator Description (1)

• The Oscillator circuit follows a classical
  transmission oscillator scheme

• Quartz Whispering Gallery Mode Resonator
• Band-pass filter to ensure that the oscillation
  on the right mode
• A 35dB gain GaAs commercial loop amplifier
• Variable attenuator, phase shifter

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EFTF 2002 Russia
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Oscillator Description (2)
RF spectrum center freq.26.00GHz span1MHz RF
level 5.00dBm res.BW.10kHz video BW.10kHz
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Phase noise measurement
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Results and discussion (1)
Typical DRO 26GHz
Sapphire 9GHz x 3
At 26 GHz, S?(1kHz)73dB.rad².Hz-1 with a 1/f3
dependence
Trade-off?
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EFTF 2002 Russia
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Results and discussion (2)

• S?(f) ? flicker level of ?y(?)2.6.10-10

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EFTF 2002 Russia
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Results and discussion (3)

• Leeson model
• ? amplifier intrinsic phase noise
  97dBrad2Hz-1
• compared with the phase noise of state-of-the-art
  amplifiers
• Possible increase the performances of our
  oscillator by the use of low noise transistors
  (GaAs HBTs?)

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EFTF 2002 Russia
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EFTF 2002 Russia