Characterization of 1.2GHz Characterization of 1.2GHz Phase Phase Locked Loops and Voltage Locked Loops and Voltage Controlled Oscillators in a Controlled Oscillators in a Total Dose Radiation Total Dose Radiation Environment Environment Martin Vandepas, Kerem Ok, Anantha Nag Nemmani, Martin Vandepas, Kerem Ok, Anantha Nag Nemmani, Merrick Brownlee, Kartikeya Mayaram, Un-Ku Moon Merrick Brownlee, Kartikeya Mayaram, Un-Ku Moon Oregon State University Oregon State University Department of Electrical and Computer Engineering Department of Electrical and Computer Engineering MAPLD 2005 MAPLD 2005 September 7-9, 2005 September 7-9, 2005
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Martin Vandepas, Kerem Ok, Anantha Nag Nemmani, Merrick Brownlee, Kartikeya Mayaram, Un-Ku Moon
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 - PowerPoint PPT Presentation
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Characterization of 1.2GHz PhaseCharacterization of 1.2GHz PhaseLocked Loops and Voltage Controlled Locked Loops and Voltage Controlled Oscillators in a Total Dose Radiation Oscillators in a Total Dose Radiation
EnvironmentEnvironment
Martin Vandepas, Kerem Ok, Anantha Nag Nemmani, Merrick Martin Vandepas, Kerem Ok, Anantha Nag Nemmani, Merrick Brownlee, Kartikeya Mayaram, Un-Ku MoonBrownlee, Kartikeya Mayaram, Un-Ku Moon
Oregon State UniversityOregon State UniversityDepartment of Electrical and Computer EngineeringDepartment of Electrical and Computer Engineering
MAPLD 2005MAPLD 2005
September 7-9, 2005September 7-9, 2005
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OutlineOutline
• Test chip descriptionTest chip description
• Radiation test setupRadiation test setup
• ResultsResults
• ConclusionConclusion
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Test Chip (Honeywell MOI-5)Test Chip (Honeywell MOI-5)
• LC oscillators LC oscillators – NMOS current sourceNMOS current source– PMOS current sourcePMOS current source– Complementary current sourceComplementary current source
layoutlayout• Body ties in SOI: with Body ties in SOI: with body tiesbody ties & without ( & without (floatingfloating body) body)
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Radiation Test SetupRadiation Test Setup
• Two testsTwo tests– 500krad(SiO500krad(SiO22) at a dose rate of 500 rad/sec) at a dose rate of 500 rad/sec
• One exposureOne exposure• Characterize the oscillators before and after Characterize the oscillators before and after
the dosethe dose
– 25krad(SiO25krad(SiO22) to 6.4Mrad(SiO) to 6.4Mrad(SiO22) doubling ) doubling
dosage each stepdosage each step• Tested current and lock range of ring PLL vs. Tested current and lock range of ring PLL vs.
total radiation dosetotal radiation dose• Quantify effect of annealing 35 days after Quantify effect of annealing 35 days after
radiation at room temperatureradiation at room temperature
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Radiation Equipment at AFRLRadiation Equipment at AFRL
• Phillips low energy X-Ray (LEXR) tubePhillips low energy X-Ray (LEXR) tube– Shown with cryo chamber (not used)Shown with cryo chamber (not used)
• Chip irradiated directly with IC lid removedChip irradiated directly with IC lid removed• All circuits biased except buffersAll circuits biased except buffers
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First TestFirst Test
• Current consumption about constant Current consumption about constant throughout irradiationthroughout irradiation– Suggests leakage current is not significant Suggests leakage current is not significant
for the given dosefor the given dose
• One notable observationOne notable observation– Shifted tuning range for ring-based Shifted tuning range for ring-based
oscillatorsoscillators
• Annealing until measurement of VCOsAnnealing until measurement of VCOs– Dependence on process makes Dependence on process makes
characterization of annealing difficultcharacterization of annealing difficult
• Circuit current Circuit current vs. total dosevs. total dose
• Very little Very little annealingannealing
105
106
58
59
60
61
62
63
64
65
Total Circuit Board Bias Current @ 45MHz FREF
Total Radiation Dose (Rad SiO2)
Curr
ent
(mA)
After 35 days annealing
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Second Test – Ring PLLSecond Test – Ring PLL
• Lock range vs. Lock range vs. total dosetotal dose
• Still locks at Still locks at 6.2MRad(SiO6.2MRad(SiO22))
• Gaps are due Gaps are due to test setupto test setup
105
106
400
500
600
700
800
900
1000
1100
1200
Lock Range
Total Radiation Dose (Rad SiO2)
Frequency
(M
Hz)
After 35 days annealing
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Total Dose Effect on PLLsTotal Dose Effect on PLLs
• Digital blocksDigital blocks– Can tolerate large shifts in threshold voltagesCan tolerate large shifts in threshold voltages– Immune to large doses of radiationImmune to large doses of radiation– Continue functioning until transistors cannot be Continue functioning until transistors cannot be
turned onturned on
• Charge Pump and Loop FilterCharge Pump and Loop Filter– Performance degradationPerformance degradation– Current mismatch & leakageCurrent mismatch & leakage– Eventual functional failureEventual functional failure
• Self calibration/tuningSelf calibration/tuning• Analog tuning mechanisms are Analog tuning mechanisms are
susceptible to total dosesusceptible to total dose• Digital blocks can inherently resist large Digital blocks can inherently resist large
doses of radiation before functional doses of radiation before functional failurefailure
• All digital PLLsAll digital PLLs ideal for total dosage ideal for total dosage hardeninghardening
• Architectures with loop parameters Architectures with loop parameters independent of environmentindependent of environment
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ConclusionsConclusions
• Analog PLL’s can be sensitive to total Analog PLL’s can be sensitive to total dose radiationdose radiation
• Designing with threshold shifts in mind Designing with threshold shifts in mind can harden themcan harden them
• New all-digital PLL techniques may New all-digital PLL techniques may present total dose hardened by design present total dose hardened by design PLLsPLLs
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AcknowledgmentAcknowledgment
• We would like to thank Ken Merkel, We would like to thank Ken Merkel, Steve Clark, Dave Alexander, and Bill Steve Clark, Dave Alexander, and Bill Kemp of the Air Force Research Lab in Kemp of the Air Force Research Lab in Albuquerque, NM for their direct Albuquerque, NM for their direct support of the radiation testingsupport of the radiation testing
• Thanks to AFRL for sponsoring this Thanks to AFRL for sponsoring this projectproject