0.7 v supply self-biased nanowatt mos-only threshold voltage monitor oscar mattia, h. klimach, s....
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0.7 V Supply Self-Biased NanoWatt MOS-Only Threshold
Voltage Monitor
Oscar Mattia, H. Klimach, S. Bampi and M. Schneider
ISCAS2015 – 0.7 V Supply Self-Biased NanoWatt MOS-Only Threshold Voltage Monitor
Electrical and Electronics Engineering Department
Federal University of Santa Catarina
Florianopolis, Brazil
ETRO / mmWave group
VUB / imecLeuven, Belgium
Electrical Engineering Dep.
Informatics InstituteFederal University of Rio
Grande do SulPorto Alegre, Brazil
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On this presentation
ISCAS2015 – 0.7 V Supply Self-Biased NanoWatt MOS-Only Threshold Voltage Monitor
This work introduces a threshold voltage
monitor circuit, and a process
independent design methodology. Features:
nanoWatt power
sub-1V power supply
self-biased and MOS-only
Applications:
bias circuits
voltage references
process
monitor/comp
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Threshold Monitor Definition
“Ideally, a threshold voltage monitor is a
circuit that delivers the estimated VT0
value as a voltage directly from its
operational conditions”
without parametric setups
without curve fitting
without subsequent calculationsISCAS2015 – 0.7 V Supply Self-Biased NanoWatt MOS-Only Threshold Voltage Monitor
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Outline
1. Background – MOSFET Model
2. Circuit Description
3. Design Methodology
4. Results
5. Conclusion
ISCAS2015 – 0.7 V Supply Self-Biased NanoWatt MOS-Only Threshold Voltage Monitor
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𝟏 . 𝐼𝐷=𝐼 𝐹− 𝐼𝑅=𝑆 𝐼𝑆𝑄 (𝑖𝑓 −𝑖𝑟 )
𝟐 .𝑉 𝐺−𝑉 𝑇 0−𝑛𝑉 𝑆 (𝐷)
𝑛∅ 𝑡
=𝐹 (𝑖 𝑓 ( 𝑟 ) )
VT0 is defined by the equality between the drift and diffusion components of the drain current.
𝑰 𝑺𝑸=𝟏𝟐𝒏𝝁𝑪𝒐𝒙∅ 𝒕
𝟐
𝟑 .𝐹 (𝑖𝑓 (𝑟 ))=√1+ 𝑖𝑓 ( 𝑟 )−2+ ln (√1+𝑖𝑓 (𝑟 )−1)ISCAS2015 – 0.7 V Supply Self-Biased NanoWatt MOS-Only Threshold Voltage Monitor
UICM MOSFET Model
Drift Current Diffusion Current
For VG = VT0
Cunha et al. JSSC 1998
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Outline
1. Background – MOSFET Model
2. Circuit Description
3. Design Methodology
4. Results
5. Conclusion
ISCAS2015 – 0.7 V Supply Self-Biased NanoWatt MOS-Only Threshold Voltage Monitor
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Self-Cascode MOSFET
E. Vittoz, J. Felrath, JSSC 1977Rossi et al, Nanotech 2007
M1 in Triode, M2 in Saturation
𝑉 𝐷1=∅ 𝑡 [𝐹 ( 𝑖𝑓 1 )−𝐹 (𝑖𝑓 2 ) ]
For VG = VT0
ISCAS2015 – 0.7 V Supply Self-Biased NanoWatt MOS-Only Threshold Voltage Monitor
VT0
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Balancing 2 Self-Cascode Cells
ISCAS2015 – 0.7 V Supply Self-Biased NanoWatt MOS-Only Threshold Voltage Monitor
M1/M2 in MI, M3/M4 in WI
𝑉 𝑥 ,12=∅ 𝑡 [𝐹 (𝑖 𝑓 1 )−𝐹 (𝑖𝑓 2 ) ]𝑉 𝑥 , 34=∅ 𝑡 [𝐹 (𝑖𝑓 3 )−𝐹 (𝑖𝑓 4 ) ]
Camacho et al. TCAS II 2005𝐵=
𝑖 𝑓 2𝑖 𝑓 3
=5
VT0
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Limits Over Temperature
ISCAS2015 – 0.7 V Supply Self-Biased NanoWatt MOS-Only Threshold Voltage Monitor
Minimum Power Supply
To keep M9 in Saturation.
(0.6 V typical, for this design ex)
Minimum Threshold Voltage
To keep M4 in Saturation.
(300 mV @ 27ºC, for this design ex)
Camacho et al. TCAS II, 2005.
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Outline
1. Background – MOSFET Model
2. Circuit Description
3. Design Methodology
4. Results
5. Conclusion
ISCAS2015 – 0.7 V Supply Self-Biased NanoWatt MOS-Only Threshold Voltage Monitor
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Design Methodology - Sizing M1-M4
ISCAS2015 – 0.7 V Supply Self-Biased NanoWatt MOS-Only Threshold Voltage Monitor
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Outline
1. Background – MOSFET Model
2. Circuit Description
3. Design Methodology
4. Results
5. Conclusion
ISCAS2015 – 0.7 V Supply Self-Biased NanoWatt MOS-Only Threshold Voltage Monitor
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Simulation Results - Temperature
-40 – 125°C
23 nW @ 27°C33 nW @ 125°C
VDD = 0.7 VVT0,nom = 426 mV
@ 27°C
ISCAS2015 – 0.7 V Supply Self-Biased NanoWatt MOS-Only Threshold Voltage Monitor
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Simulation Results – Power Supply
LSVG1 = 3.6 mV/VLSITOTAL = 2.6 nA/VVDD = 0.6 - 1.2 V
PSRR @ 100 HzVG1 = -38.9 dB
VDD = 0.7 V
ISCAS2015 – 0.7 V Supply Self-Biased NanoWatt MOS-Only Threshold Voltage Monitor
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Simulation Results – 300 MC Runs
AverageProcess
Variation
LocalRandomVariation
-40°C
Combined
Variation
LOWSPREAD
27°C 125°C
𝜺𝒎𝒂𝒙 (∓𝟑𝝈 )=𝟎 .𝟓∓𝟏𝟗 .𝟓𝒎𝑽
ISCAS2015 – 0.7 V Supply Self-Biased NanoWatt MOS-Only Threshold Voltage Monitor
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Outline
1. Background – MOSFET Model
2. Circuit Description
3. Design Methodology
4. Results
5. Conclusion
ISCAS2015 – 0.7 V Supply Self-Biased NanoWatt MOS-Only Threshold Voltage Monitor
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Conclusion – Topology
MOS-Only VT0 Monitor topology:
sub-1V Power Supply
nanoWatt Power Consumption
technology independent sizing
ISCAS2015 – 0.7 V Supply Self-Biased NanoWatt MOS-Only Threshold Voltage Monitor
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Conclusion – Performance
ISCAS2015 – 0.7 V Supply Self-Biased NanoWatt MOS-Only Threshold Voltage Monitor
Simulation results show that:
tracks VT0 with average process variations
local mismatch main cause for variability
switching techniques (DEM, auto-zero, etc) and op-amps can enhance performance
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Acknowledgments
CNPq for financial support
imec for financial support
CI-BRASIL Program for PDK licensing
MOSIS Educational Program for PDK
licensing
Vicente Cunha for simulations
ISCAS2015 – 0.7 V Supply Self-Biased NanoWatt MOS-Only Threshold Voltage Monitor
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THANK YOU
ISCAS2015 – 0.7 V Supply Self-Biased NanoWatt MOS-Only Threshold Voltage Monitor
mmWave group
imec
3000 Leuven
Belgium
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Backup – Extraction Method
ISCAS2015 – 0.7 V Supply Self-Biased NanoWatt MOS-Only Threshold Voltage Monitor
VGB (V)
Siebel et al. Microelectronics Journal 2012
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Backup – Sizing Tables
ISCAS2015 – 0.7 V Supply Self-Biased NanoWatt MOS-Only Threshold Voltage Monitor