Phase Noise measurements using Fiber Optic Delay Lines With - - PowerPoint PPT Presentation

Phase Noise measurements using Fiber Optic Delay Lines

Guillaume De Giovanni www.NoiseXT.com

Noise eXtended Technologies

With contributions from

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Phase Noise measurements

• 2 phase noise measurement types:

– Absolute also called total phase noise or output phase noise – Residual also called added phase noise

• 2 types of DUT:

– Sources: Oscillators, Synthesizers, frequency translation devices viewed as a frequency sources (their Local Oscillator) – Others: Amplifiers, cables, frequency translation devices, all viewed as a 2 ports phase coherent device (output vs input)

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Absolute Phase Noise demodulation

• Direct Phase detection:

– Compares a reference signal to the signal to test

• Traditional phase noise analyzers
• Requires a “same or better phase noise” frequency

source with DC-coupled FM port

• Measures the phase noise sum of the Reference and the

DUT

• FM discriminator Phase extraction:

– Measures Frequency variations (noise) – Does not need any reference signal

• State of the Art dynamic range solution

Frequency to Phase Conversion

PHASE FREQUENCY

• Limited performance very close to the carrier but

excellent dynamic range at mid/high offsets.

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Frequency discriminator

• Phase Noise measurement based on Frequency

Noise Measurement

Path 1 Path 2

Noise voltage (fm) =

fm fm πτ πτ ) sin(

Kφ 2πτΔf(fm)

τ = Path 2 – Path 1 in seconds

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Measurement Diagram

Front-end DCNTS

DCNTS (receiver section) noise floor

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0.0

• 200.0
• 190.0
• 180.0
• 170.0
• 160.0
• 150.0
• 140.0
• 130.0
• 120.0
• 110.0
• 100.0
• 90.0
• 80.0
• 70.0
• 60.0
• 50.0
• 40.0
• 30.0
• 20.0
• 10.0

100M 10 100 1k 10k 100k 1M 10M

L(fm) dBc/Hz Spectrum Type DCNTS Residual Phase Noise floor

Rev 5.5.5b / 9july15

Configuration of : Comments : Residual Phase Noise at 3.8GHz using a DRO source and comparing the cross-correlation test to both single channel tests

Phase Kphi : 0.273 / 0.286 Offset Ref : 0.0dB Ref Spurs : 10.0dB Date: 10 Mar 2015; 13 h 33; meas. time: 11mn 3s XCOR 3G8 Res PN with filter DCNTS SN : 12I00A0821 calibrated :11 Dec 2015

Ch B 3.8GHz XCOR 3G8 Res PN with filter Ch A 3.8GHz

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Keys to success

• Lasers with low Rin and low noise external modulator
• Thermally stabilized fiber spools
• Ultra low noise amplifiers (after photodiodes)
• Uncorrelated channels, no cross-talk

– Use of Innovative Fiber Spools with orthogonal behavior

• Software controlled Phase shifters
• Optimized Signal Processing Flow

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Fiber Delay Residual Phase Noise

Average L(fm) for 1 fiber link: 10 Hz

• 126 dBc/Hz

100

• 136

1k

• 142

10k

• 146

100k

• 148

RF over fiber link “own” phase noise requires 2 links Joint work with Femto-ST, Besancon, France

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1

10

2

10

3

10

4

10

5

−160 −150 −140 −130 −120 −110 −100 −90 −80 −70 Fréquence (Hz) Sφ (dB rad2/Hz) Bras B Bras A

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Absolute Phase Noise floor

L(fm) for 50 us (10 km) single fiber channel: 10 Hz

• 75 dBc/Hz

100

• 107

1k

• 132

10k

• 152

100k N/A for 50 us Still with no cross-correlations ! But 10,000 xcor = 20dB better Potential noise floor:

• 172 dBc/Hz @10kHz offset

Simulation 10

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Absolute Phase Noise floor

L(fm) for 10 us (2 km) and 200 xcor, simulation is: 10 Hz

• 75 dBc/Hz

100

• 105

1k

• 132

10k

• 155

Measurement matches Simulation within 2 dB

Note: Measurement is from an older prototype than actual measured data used in simulation and fiber link had a higher residual noise but matches Simulation on old data within 2 dB.

Measured (using a State of the Art source or 2 sources) Courtesy of JPL & Cal Tech for NASA

0.0

• 190.0
• 180.0
• 170.0
• 160.0
• 150.0
• 140.0
• 130.0
• 120.0
• 110.0
• 100.0
• 90.0
• 80.0
• 70.0
• 60.0
• 50.0
• 40.0
• 30.0
• 20.0
• 10.0

1M 10 100 1k 10k 100k

L(fm) dBc/Hz Spectrum Type E8257D measured with a single EOE Delay Line

Rev 5.5.5b / 9july15

Configuration of : Comments : Frequency is 10 GHz EOE DL was 20 us pink is measured phase noise (with Sinc compensation)

• range is raw FM demodulation

Single channel measurement

Phase Kphi : 0.182 / 0.000 Offset Ref : 0.0dB Ref Spurs : 10.0dB Date: 16 Jul 2015; 15 h 12; meas. time: 43s 20u 10G amp zx60 FM DCNTS SN : 12I00A0821 calibrated :11 Dec 2012

20u 10G amp zx60 PM 20u 10G amp zx60 FM

Test Source at 10 GHz with 1x 20us DL

PHASE FREQUENCY SinX/X response

12 Joint work with Thales Research & Technology, Palaiseau, France

0.0

• 190.0
• 180.0
• 170.0
• 160.0
• 150.0
• 140.0
• 130.0
• 120.0
• 110.0
• 100.0
• 90.0
• 80.0
• 70.0
• 60.0
• 50.0
• 40.0
• 30.0
• 20.0
• 10.0

1M 10 100 1k 10k 100k

L(fm) dBc/Hz Spectrum Type OEO Source at 10 GHz measured with DCNTS

Rev 5.5.5b / 9july15

Configuration of : Comments : Frequency is 10 GHz

• scillator is experimental

EOE DLs were 5 us Dual channel measurement

Phase Kphi : 0.216 / 0.243 Offset Ref : 0.0dB Ref Spurs : 100.0dB Date: 16 Jul 2015; 17 h 52; meas. time: 2mn 14s

• sc4

DCNTS SN : 12I00A0821 calibrated :11 Dec 2012

OEO at 10 GHz with 2x 5us DL

OEO modes spurious

• 138dBc/Hz

@ 10kHz

13 Joint work with Thales Research & Technology, Palaiseau, France

Conclusion

• Fiber Optics can help measure Ultra-low Phase Noise
• State of the Art Phase Noise measurements can be

done without the need of expensive reference sources

• The design of the Fiber Optics links is key in obtaining

high performance

• We are looking for partners and customers to put such

instrument on the market:

• 170dBc/Hz @10kHz offset for an X band signal

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Thank you !

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Questions and Answers