Phase/Frequency Detector

1
Characterization of 1.2GHz PhaseLocked 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
• Programmable N ICP

• LC-VCO PLL
• Programmable N ICP

6
Prototype PLL Summary
Ring-oscillator PLL LC-tank PLL
VCO tuning range 0.43GHz 1.12GHz 1.2GHz 1.45GHz (simulated)
Power consumption 26mW _at_ 800MHz 35 mW _at_ 1.2GHz
Layout area 600mm 500mm 1000mm 1100mm
Process Honeywell MOI-5 0.35µm process Honeywell MOI-5 0.35µm process
Total pin count 25 (8 inputs, 7 outputs, 10 power) 25 (8 inputs, 7 outputs, 10 power)
7
Prototype LC VCOs
PMOS current source
Complementary current sources
NMOS current source
8
Prototype Ring Oscillators
Maneatis cell
Lee/Kim cell
Linear-load

• 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 1500
NMOS Source Body Tied 3.14 21.73 28.3 1500
NMOS Source Floating Body - - - -
Complementary Body Tied 3.30 22.58 46.13 1500
Complementary Floating Body - - - -
19
Period Jitter Ring VCOs
CHIP 1 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 26.40 800
Lee/Kim Optimized Body Tied 2.40 15.86 23.43 800
Lee/Kim Optimized Floating Body 2.68 17.80 21.45 800
Linear-Load (Maneatis) Body Tied 2.79 19.52 102 1200
Linear-Load (Maneatis) Floating 3.38 22.31 102 1200
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 21.08 26.90 1500
NMOS Source Body Tied 3.30 26.13 27.92 1500
NMOS Source Floating Body 3.07 20.00 27.69 1500
Complementary Body Tied 3.29 22.34 37.95 1500
Complementary Floating Body 2.94 17.89 37.95 1500
21
Period Jitter Ring VCOs
CHIP 2 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 26.70 800
Lee/Kim Symmetric Body Tied 2.53 18.00 22.77 800
Lee/Kim Symmetric Floating Body 2.91 19.68 21.78 800
Linear-Load (Maneatis) Body Tied 5.27 37.03 100 1200
Linear-Load (Maneatis) Floating 6.01 40.70 99 1200
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 PLLs 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