1. Characterization of 1.2GHz Phase Locked Loops and Voltage Controlled Oscillators in a Total Dose Radiation Environment
Martin Vandepas, Kerem Ok, Anantha Nag Nemmani, Merrick Brownlee, Kartikeya Mayaram, Un-Ku Moon
Oregon State University
Department of Electrical and Computer Engineering
MAPLD 2005
September 7-9, 2005

2. Outline
Test chip description
Radiation test setup
Results
Conclusion

3. Test Chip (Honeywell MOI-5)
PLLs
LC oscillator PLL
Ring oscillator PLL
LC oscillators
NMOS current source
PMOS current source
Complementary current source
Ring oscillators
Maneatis delay cell
Linear-load modified Maneatis delay cell
Lee-Kim delay cell

4. Test Chip Die Photo
LC oscillators
Ring
oscillators
LC PLL
Ring PLL

5. Prototype PLLs Ring-VCO PLL LC-VCO PLL Programmable “N” & “ICP”

6. Honeywell MOI-5 0.35µm process 25 (8 inputs, 7 outputs, 10 power)
Prototype PLL Summary
Ring-oscillator PLL
LC-tank PLL
VCO tuning range
0.43GHz – 1.12GHz
1.2GHz – 1.45GHz (simulated)
Power consumption
26mW
@ 800MHz
35 mW @ 1.2GHz
Layout area
600mm × 500mm
1000mm × 1100mm
Process
Honeywell MOI µm process
Total pin count
25 (8 inputs, 7 outputs, 10 power)

7. Complementary current sources
Prototype LC VCOs
NMOS current source
PMOS current source
Complementary current sources

8. Prototype Ring Oscillators
Maneatis cell
Linear-load
Lee/Kim cell
Maneatis delay cell: symmetric & linear loads
Lee/Kim delay cell: traditional & signal-delay-optimized layout
Body ties in SOI: with body ties & without (floating body)

9. Radiation Test Setup Two tests
500krad(SiO2) at a dose rate of 500 rad/sec
One exposure
Characterize the oscillators before and after the dose
25krad(SiO2) to 6.4Mrad(SiO2) doubling dosage each step
Tested current and lock range of ring PLL vs. total radiation dose
Quantify effect of annealing 35 days after radiation at room temperature

10. Radiation Equipment at AFRL
Phillips low energy X-Ray (LEXR) tube
Shown with cryo chamber (not used)
Chip irradiated directly with IC lid removed
All circuits biased except buffers

11. First Test Current consumption about constant throughout irradiation
Suggests leakage current is not significant for the given dose
One notable observation
Shifted tuning range for ring-based oscillators
Annealing until measurement of VCOs
Dependence on process makes characterization of annealing difficult

12. PMOS Source LC VCO

13. NMOS Source LC VCO

14. Complementary Source LC VCO

15. Lee/Kim Traditional Layout

16. Lee/Kim Signal-Path-Optimized Layout

17. Linear-Load Modified-Maneatis Oscillator

18. Period Jitter: LC VCOs CHIP 1 PRE-Radiation RMS (ps) Peak-to-peak (ps)
Power (mW)
Frequency (MHz)
PMOS Source Body Tied
2.75
18.90
29.4
1500
PMOS Source Floating Body
3.00
21.72
28.1
NMOS Source Body Tied
3.14
21.73
28.3
NMOS Source Floating Body -
Complementary Body Tied
3.30
22.58
46.13
Complementary Floating Body

19. Period Jitter: Ring VCOs
CHIP PRE-Radiation
RMS (ps)
Peak-to-peak (ps)
Power (mW)
Frequency (MHz)
Lee/Kim Traditional Body Tied
2.59
16.79
26.90
800
Lee/Kim Traditional Floating Body
2.58
16.49
26.40
Lee/Kim Optimized Body Tied
2.40
15.86
23.43
Lee/Kim Optimized Floating Body
2.68
17.80
21.45
Linear-Load (Maneatis) Body Tied
2.79
19.52
102
1200
Linear-Load (Maneatis) Floating
3.38
22.31

20. Period Jitter: LC VCOs CHIP 2 POST-Radiation RMS (ps)
Peak-to-peak (ps)
Power (mW)
Frequency (MHz)
PMOS Source Body Tied
3.25
21.08
26.67
1500
PMOS Source Floating Body
3.05
26.90
NMOS Source Body Tied
3.30
26.13
27.92
NMOS Source Floating Body
3.07
20.00
27.69
Complementary Body Tied
3.29
22.34
37.95
Complementary Floating Body
2.94
17.89

21. Period Jitter: Ring VCOs
CHIP POST-Radiation
RMS (ps)
Peak-to-peak (ps)
Power (mW)
Frequency (MHz)
Lee/Kim Traditional Body Tied
3.13
21.92
26.40
800
Lee/Kim Traditional Floating Body
2.74
17.80
26.70
Lee/Kim Symmetric Body Tied
2.53
18.00
22.77
Lee/Kim Symmetric Floating Body
2.91
19.68
21.78
Linear-Load (Maneatis) Body Tied
5.27
37.03
100
1200
Linear-Load (Maneatis) Floating
6.01
40.70 99

22. Second Test – Ring PLL Circuit current vs. total dose
Very little annealing
After 35 days annealing

23. Second Test – Ring PLL Lock range vs. total dose
Still locks at 6.2MRad(SiO2)
Gaps are due to test setup
After 35 days annealing

24. Total Dose Effect on PLLs
Digital blocks
Can tolerate large shifts in threshold voltages
Immune to large doses of radiation
Continue functioning until transistors cannot be turned on
Charge Pump and Loop Filter
Performance degradation
Current mismatch & leakage
Eventual functional failure
VCO
Tuning curve (fOSC, KVCO) changes

25. Total Dose Hardening Self calibration/tuning
Analog tuning mechanisms are susceptible to total dose
Digital blocks can inherently resist large doses of radiation before functional failure
All digital PLLs ideal for total dosage hardening
Architectures with loop parameters independent of environment

26. Conclusions Analog PLL’s can be sensitive to total dose radiation
Designing with threshold shifts in mind can harden them
New all-digital PLL techniques may present total dose hardened by design PLLs

27. Acknowledgment
We would like to thank Ken Merkel, Steve Clark, Dave Alexander, and Bill Kemp of the Air Force Research Lab in Albuquerque, NM for their direct support of the radiation testing
Thanks to AFRL for sponsoring this project