THE SA.45S CHIP-SCALE ATOMIC CLOCK

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1 THE SA.45S CHIP-SCALE ATOMIC CLOCK 2011 Stanford PNT Symposium November 18, 2011 Menlo Park, CA Robert Lutwak Symmetricom - Technology Realization Center Rlutwak@Symmetricom.com

2 CSAC for PNT

3 Physics in REALLY small cells? J. Kitching, S. Knappe, and L. Hollberg, "Performance of small-scale frequency references," presented at IEEE International Frequency Control Symposium, New Orleans, LA, J. Kitching, S. Knappe, and L. Hollberg, "Miniature vaporcell atomic-frequency references," Applied Physics Letters, vol. 81, pp ,

DARPA MTO CSAC Program Target Specifications Device Volume: < 1cm 3 Total Power Consumption: < 30 mw Stability: Multiple Competitive Contracts National Institute of

4 DARPA MTO CSAC Program Target Specifications Device Volume: < 1cm 3 Total Power Consumption: < 30 mw Stability: Multiple Competitive Contracts National Institute of Standards and Technology (NIST)/U. of Colorado Symmetricom/Draper/Sandia Teledyne Scientific/Rockwell Collins/Agilent Honeywell Sarnoff/Princeton/Frequency Electronics 4

5 The CSAC Challenge CSAC Lower Power & Better Performance 5

6 Navigation Applications Enhanced GPS Receivers Navigation with <4 Satellites Rapid P(y) code acquisition Spoof detection Timing holdover in GPS-denied environments Integrated Inertial Navigation Randy Rollo (SPAWAR) Navigation nugget Combine GPS, inertial nav, CSAC in manpack navigator Underwater GPS-like navigation Jeff Holland (NAVSEA Keyport) Acoustic timing beacons Ad-hoc navigation systems Self-assembling networks of first responders/dod operations 6

7 Other Applications Secure Communications Time-Sequence Code Acquisition in GPS-denied environments Frequency-hopping radios Datalogging Time-tagging Synthesized aperture arrays of sensors (seismology) Traingulation of signals Underwater timing applications Data-logging Automobile collision avoidance systems Telecom/Enterprise GPS timing holdover Clean-up timing source for PTP Time/Frequency in high vibration environments 7

8 A bit of History Era Activity Result Reporting DARPA CSAC Phase-I Basic physics MEMS Components PTTI 2002 PTTI DARPA CSAC Phase-II 10 mw Physics Package PTTI DARPA CSAC Phase-II Autonomous CSAC PTTI DARPA CSAC Phase-III DARPA CSAC Phase-IV Build of 10X prototypes 30 mw 1 cm 3 demo Ruggedization and environmental testing PTTI Symmetricom Productization SA.45s 1/18/2011 Product Announcement 8

9 The 10 mw Physics Package 9

10 Ditch the cavity Cyr & Tetu

11 RF vs. CPT Requires Resonant Cavity High-Bandwidth VCSEL is Enabling Technology 11

The 10 mw Physics Package Tensioned polyimide suspension Microfabricated Silicon vapor cell Low-power Vertical-Cavity Surface Emitting Laser (VCSEL) Vacuum-packaged to eliminate convection/conduction

12 The 10 mw Physics Package Tensioned polyimide suspension Microfabricated Silicon vapor cell Low-power Vertical-Cavity Surface Emitting Laser (VCSEL) Vacuum-packaged to eliminate convection/conduction Overall Thermal Resistance 5000 C/W US Patent # M. Mescher, et. Al., "An Ultra-Low-Power Physics Package for a Chip-Scale Atomic Clock," Proceedings of the 13th International Conference on Solid-State Sensors, Actuators and Microsystems (Transducers '05), Seoul, Korea, June 5-9, 2005, pp

13 Polyimide Suspension Polyimide suspension VCSEL and Thermistor on Polyimide suspension Photos courtesy of Draper Laboratory 13

14 SA.45s Physics Package Cover Photodiode Upper Suspension Resonance Cell Cell Spacer Frame Spacer Lower Suspension VCSEL LCC 14

15 Physics Package Performance PPIII CPT Resonance Resonance Q = 5x10 7 Stability vs. Time 15

16 Production Statistics: Physics Package Power 16

17 SA.45s CSAC 17

18 Control System Laser Servo - Lock laser wavelength to optical absorption resonance via DC Bias Temperature Servo - Optimize optical power via temperature Clock Servo Lock local oscillator to CPT resonance Power Servo - Optimize CPT signal amplitude via µwave power 18

19 SA.45s CSAC Block Diagram Microwave System: 50 mw Control System: 40 mw Physics: 10 mw Regulators & Passives: 15 mw Total: 115 mw 19

20 SA.45s CSAC Lid Top Shield C Field Coil Physics Package PCB Lower Shield Baseplate 20

21 SA.45s Performance 21

22 Short-term Stability 22

23 Production Statistics: 1-second Stability 23

24 Production Statistics: 10-second Stability 24

25 Timing Error 25

26 Medium- to Long-Term Stability SN 1008CS00066 Now on ISS 26

27 Impact of Drift on Timing Error 27

28 REALLY Long-term Stability SN 084 Early functional prototype 28

29 Typical Temperature Sensitivity 29

30 Production Statistics: Temperature Sensitivity 30

31 Production Statistics: Power Consumption 31

32 Other interesting measurements 32

1 Pulse-per-Second System CSAC-dominated regime σ y (τ) 10-10 / τ 1/2 GPS-dominated regime σ y (τ) 10-8 / τ

400 ps (better than CSAC for τ > 10 s) Self-calibration for mission initialization Discipline to GPS as holdover

33 1 Pulse-per-Second System CSAC-dominated regime σ y (τ) / τ 1/2 GPS-dominated regime σ y (τ) 10-8 / τ Synchronization Resolution +/- 50 ns Initial synchronization +/- 50 ns Internal 1 PPS measurement system Resolution 400 ps (better than CSAC for τ > 10 s) Self-calibration for mission initialization Discipline to GPS as holdover oscillator Discipline to GPS Self-calibration to reference 1 PPS Initial phase and frequency error steered away within 1000 seconds 33

34 Performance under Vibration 5X Production SA.45s CSACs tested to Mil-STD-810 Fig E-1, 7.7 grms and 15.4 grms All 5X Units hold lock up to 15.4 grms Most units meet static ADEV spec in most axes up to 7.7 grms! 34

35 Exposure to Ionizing Radiation Frequency Shift 2.5x10-11 /krad 2X Production SA.45s CSACs were exposed to Total Ionizing Dose (TID) Gamma radiation testing Both units failed between 11 krad and 12 krad TID due to same op-amp (not Physics!) Minimal additional mu-metal shielding should permit LEO orbit applications at krad TID 35

36 Status and Future History SA.45s CSAC is available now $1500 list price Lead times are still a little long (6-8 weeks) Manufacturing Technology (ManTech) program underway Funded by USArmy/OSD/GPS-W Objective: $100 sell price, Threshold: $300 sell price Tactical-Grade Atomic Clock (TGAC) Program Funded by Office of Naval Research Objective is smaller, lower-power, improved performance Integrated Micro-Primary Atomic Clock (IMPACT) Program Funded by DARPA MTO Objective is CSAC with 1000X improvement in drift, retrace, and temperature sensitivity 36

37 Acknowledgements CSAC Development Team: Symmetricom: A. Rashed, P. Vlitas, J. Deng, D. Emmons, T. Gebrewold, and R.M. Garvey Draper Laboratory: M. Varghese, G. Tepolt, J. Leblanc, and M. Mescher Sandia National Laboratories: G.M.Peake, K.M. Geib, and D.K. Serkland Symmetricom Productization Team: Design and Process Engineering: M. Silveira, D. Taylor, S. Chang, M. Juppe, J. McCartney, E. Saw, N. Dao, E. Arena, R. Dumont, M. Jiang, M. Stanczyk, L. Zanca, J. Malcolmson, and J. Dansereau Manufacturing Engineering and Operations: M-J. Bennett, S. Wilson, R. Dumont, S. Fox, E. Arena, T. Iovanella, J. McGuire, and M. Duval 37

38 Robert Lutwak and the rest of the CSAC Team. Symmetricom, Inc Orchard Parkway San Jose, CA Tel: Fax:

THE SA.45S CHIP-SCALE ATOMIC CLOCK EARLY PRODUCTION STATISTICS

THE SA.45S CHIP-SCALE ATOMIC CLOCK EARLY PRODUCTION STATISTICS Robert Lutwak Symmetricom Email: RLutwak@Symmetricom.com Abstract Since the announcement of general availability of the SA.45s Chip-Scale