Phoenix: An Ultra-Low Power Processor for Cubic Millimeter Sensor System

1
Phoenix An Ultra-Low Power Processor for Cubic
Millimeter Sensor System
Bravo pH Monitoring System
VeriChipTM RFID Tag VeriChip

• 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

2

• Comprehensive standby strategy
• Optimum technology selection
• L0.18µm, Vdd0.5V given performance, duty cycle
  and memory requirements
• Unique power gating approach
• SVT MOSFET with W0.66µm L0.5µm
• 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

3

• Results
• 29.6pW for standby mode and 2.8pJ/cycle for
  active mode
• 100kHz at Vdd0.5V
• 1mm2 in 0.18µm CMOS technology
• 2000 instructions for every 10min gives
  Eactive5.6nJ, Estandby17.8nJ
• 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!