RF-Powered Micromechanical Clock Generator

Patent Status

Brief Description

Realizing the potential of massive sensor networks requires overcoming cost and power challenges. When sleep/wake strategies can adequately limit a network node's sensor and wireless power consumption, then the power limitation comes down to the real-time clock (RTC) that synchronizes sleep/wake cycles. With typical RTC battery consumption on the order of 1µW, a low-cost printed battery with perhaps 1J of energy would last about 11 days. However, if a clock could bleed only 10nW from this battery, then it would last 3 years.

To attain such a clock, researchers at UC Berkeley developed a mechanical circuit that harnesses squegging to convert received RF energy (at -58dBm) into a local clock while consuming less than 17.5nW of local battery power. The Berkeley design dispenses with the conventional closed-loop positive feedback approach to realize an RCT (along with its associated power consumption) and removes the need for a sustaining amplifier altogether. 

Suggested uses

- Ulta-low power oscillators for clocking applications that benefit from replacing power hungry clocks in any electronic system.

- Clocking in harsh environments (e.g. radioactive, extreme heat) where conventional electronic clocks can't operate, but this all-mechanical clock can operate.

Advantages

- Low power

- Low cost

- All mechanical design

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