Noise eXtended Technologies Phase Noise measurements using Fiber Optic Delay Lines With contributions from Guillaume De Giovanni www.NoiseXT.com
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) 2
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 3
Frequency to Phase Conversion PHASE FREQUENCY • Limited performance very close to the carrier but excellent dynamic range at mid/high offsets.
Frequency discriminator • Phase Noise measurement based on Frequency Noise Measurement Path 2 τ = Path 2 – Path 1 in seconds Path 1 sin( fm ) πτ K φ 2 πτΔ f(fm) Noise voltage (fm) = fm πτ 5
Measurement Diagram Front-end DCNTS 6
DCNTS (receiver section) noise floor DCNTS Residual Phase Noise floor Spectrum Type L(fm) dBc/Hz DCNTS 0.0 Ch A 3.8GHz -10.0 Ch B 3.8GHz -20.0 XCOR 3G8 Res PN with filter -30.0 -40.0 -50.0 -60.0 -70.0 -80.0 -90.0 -100.0 -110.0 -120.0 -130.0 -140.0 -150.0 -160.0 -170.0 -180.0 -190.0 -200.0 10 100 1k 10k 100k 1M 10M 100M Comments : Residual Phase Noise at Configuration of : XCOR 3G8 Res PN with filter 3.8GHz using a DRO source and 7 comparing the cross-correlation test to Phase both single channel tests Kphi : 0.273 / 0.286 Offset Ref : 0.0dB Ref Spurs : 10.0dB Date: 10 Mar 2015; 13 h 33; meas. time: 11mn 3s SN : 12I00A0821 calibrated :11 Dec 2015 Rev 5.5.5b / 9july15
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 8
Fiber Delay Residual Phase Noise RF over fiber link “own” phase noise requires 2 links − 70 Bras B − 80 Bras A − 90 − 100 S φ (dB rad 2 /Hz) − 110 − 120 − 130 − 140 − 150 − 160 1 2 3 4 5 10 10 10 10 10 Fréquence (Hz) Average L(fm) for 1 fiber link: 10 Hz -126 dBc/Hz 100 -136 1k -142 10k -146 100k -148 Joint work with Femto-ST, Besancon, France 9
Absolute Phase Noise floor Simulation 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 10 10
Absolute Phase Noise floor Measured (using a State of the Art source or 2 sources) 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. Courtesy of JPL & Cal Tech for NASA 11
Test Source at 10 GHz with 1x 20us DL E8257D measured with a single EOE Delay Line Spectrum Type L(fm) dBc/Hz DCNTS 0.0 20u 10G amp zx60 FM -10.0 20u 10G amp zx60 PM -20.0 -30.0 -40.0 PHASE -50.0 -60.0 -70.0 -80.0 -90.0 -100.0 -110.0 -120.0 FREQUENCY -130.0 -140.0 -150.0 -160.0 SinX/X response -170.0 -180.0 -190.0 10 100 1k 10k 100k 1M Joint work with Thales Research & Technology, Palaiseau, France Comments : Configuration of : 20u 10G amp zx60 FM Frequency is 10 GHz 12 EOE DL was 20 us Phase pink is measured phase noise (with Sinc Kphi : 0.182 / 0.000 compensation) Offset Ref : 0.0dB orange is raw FM demodulation Ref Spurs : 10.0dB Single channel measurement Date: 16 Jul 2015; 15 h 12; meas. time: 43s SN : 12I00A0821 calibrated :11 Dec 2012 Rev 5.5.5b / 9july15
OEO at 10 GHz with 2x 5us DL OEO Source at 10 GHz measured with DCNTS Spectrum Type L(fm) dBc/Hz DCNTS 0.0 -10.0 -20.0 -30.0 -40.0 -50.0 -60.0 -70.0 OEO -80.0 modes -90.0 spurious -100.0 -110.0 -120.0 -130.0 -140.0 -138dBc/Hz -150.0 @ 10kHz -160.0 -170.0 -180.0 -190.0 10 100 1k 10k 100k 1M Joint work with Thales Research & Technology, Palaiseau, France Comments : Configuration of : osc4 Frequency is 10 GHz 13 oscillator is experimental Phase EOE DLs were 5 us Kphi : 0.216 / 0.243 Dual channel measurement Offset Ref : 0.0dB Ref Spurs : 100.0dB Date: 16 Jul 2015; 17 h 52; meas. time: 2mn 14s SN : 12I00A0821 calibrated :11 Dec 2012 Rev 5.5.5b / 9july15
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 14
Thank you ! Questions and Answers 15
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