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Phoenix: An Ultra-Low Power Processor for Cubic Millimeter Sensor System. Motivations Sensor application requires small form factor and long lifetime Both limited by battery - A 1mm 2 zinc/silver battery with 100µAh/cm 2 can provides 177pW for 1 year lifetime
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Phoenix: An Ultra-Low Power Processor for Cubic Millimeter Sensor System Motivations • Sensor application requires small form factor and long lifetime • Both limited by battery - A 1mm2 zinc/silver battery with 100µAh/cm2 can provides 177pW for 1 year lifetime • Either improve battery or power consumption • Minimize standby power (dominating portion of total power) via comprehensive standby strategy Bravo® pH Monitoring System VeriChipTM RFID Tag VeriChip
Comprehensive standby strategy • Optimum technology selection • L=0.18µm, Vdd=0.5V given performance, duty cycle and memory requirements • Unique power gating approach • SVT MOSFET with W=0.66µm L=0.5µm • Tradeoff performance with standby power • Ultra-low leakage sub-VTH SRAM design • 7.1fW/bit custom SRAM cell • Adaptive power gating for dynamic standby power management • Power gating for peripherals • Robust ultra-low Vdd ROM design • full static NAND ROM design for robustness • Simple ISA with compression support • Narrow instruction for small IMEM footprint • Ultra-low power peripheral unit design • Slow watchdog timer • Low power temperature sensor
Results • 29.6pW for standby mode and 2.8pJ/cycle for active mode • 100kHz at Vdd=0.5V • 1mm2 in 0.18µm CMOS technology • 2000 instructions for every 10min gives Eactive=5.6nJ, Estandby=17.8nJ • Theoretically 15 year lifetime with a 1mm2 thin film lithium battery Future works – designing more low power sub-modules including communication link, improve existing modules, variation compensation method, and system-level integration Thank you!