Self-powered timers and methods of use
A timer module including a timer and a compensation circuit coupled to the timer is provided. The timer measures time over a first monitoring period. The timer includes a floating-gate and an energy barrier. The floating-gate stores electrons and has an initial state and a measured state. The measured state includes a current time and a current floating-gate voltage. The energy barrier is positioned adjacent the floating-gate and leaks electrons from an ambient environment of the timer to the floating-gate at a predetermined leakage rate using Fowler-Nordheim (FN) tunneling. The compensation circuit selectably adjusts the first monitoring period to facilitate improved robustness of the timer with respect to fabrication mismatch due to the self-compensating dynamics of FN tunneling.
1. A timer module comprising:
a timer configured to measure time over a first monitoring period, the timer comprising:
a floating-gate configured to store electrons, the floating-gate having an initial state and a measured state, the measured state including a current time and a current floating-gate voltage; and
an energy barrier positioned adjacent the floating-gate, the energy barrier configured to leak the electrons from an ambient environment of the timer to the floating-gate at a predetermined leakage rate using Fowler-Nordheim (FN) tunneling; and
a compensation circuit coupled to the timer, the compensation circuit configured to selectably adjust the first monitoring period.
2. The timer module in accordance with claim 1 , wherein the compensation circuit comprises a varactor configured to adjust a first capacitance of the floating-gate to a second capacitance, wherein the first monitoring period is adjusted to a second monitoring period based on the second capacitance.
3. The timer module in accordance with claim 1 , wherein the predetermined leakage rate is fixed with respect to variable capacitance of the floating-gate and variable tunneling junction area of the energy barrier.
4. The timer module in accordance with claim 1 , wherein the compensation circuit comprises a series capacitor network.
5. The timer module in accordance with claim 1 , wherein floating-gate is comprised of a strip of poly-crystalline silicon.
6. The timer module in accordance with claim 1 , wherein the energy barrier is a triangular quantum-mechanical energy barrier comprised of silicon-dioxide.
7. The timer module in accordance with claim 6 , wherein a base of the triangular quantum-mechanical energy barrier is greater than 10 nanometers.
8. The timer module in accordance with claim 1 , further comprising:
a plurality of timers; and
calibration data correlating variance among the plurality of timers with a predicted time.
9. A timer module comprising:
a plurality of timer circuits operable to output a time dependent voltage, each timer circuit comprising:
a floating-gate configured to store electrons, the floating-gate having an initial state and a measured state, the measured state including a current time and a current floating-gate voltage; and
a triangular quantum-mechanical energy barrier positioned adjacent the floating-gate, the triangular quantum-mechanical energy barrier configured to leak the electrons from an ambient environment of the timer to the floating-gate at a predetermined leakage rate using Fowler-Nordheim (FN) tunneling;
a plurality of variable capacitors coupled to the plurality of timer circuits, the plurality of variable capacitors operable to adjust a floating gate capacitance of each timer circuit.
10. The timer module of claim 9 , wherein the floating-gate is comprised of a strip of poly-crystalline silicon.
11. The timer module of claim 9 , wherein the triangular quantum-mechanical energy barrier is comprised of silicon-dioxide.
12. The timer module of claim 11 , wherein a base of the triangular quantum-mechanical energy barrier is greater than 10 nanometers.