Active RF tag with wake-up circuit to prolong battery life
US6593845B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 29, 1999 |
| Grant date | Jul 15, 2003 |
| Priority date | — |
| Expiry date | Sep 29, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG07C2009/00793
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
An active RF transponder is provided with a wake-up circuit that wakes the RF transponder from a sleep state upon detection of an RF interrogating signal. The active RF transponder includes a battery, an antenna adapted to receive RF signals from an interrogator, and electronic circuitry providing the various RF transponder functions of sending/receiving signals and storing data. A first embodiment of the invention includes a wake-up circuit that periodically checks for the presence of an RF signal at the antenna. The wake-up circuit is coupled to the antenna and includes a switch adapted to selectively couple the battery to the electronic circuitry and provide electrical power thereto upon detection of the RF signals by the antenna. The wake-up circuit further comprises an oscillator providing a clock signal having a low duty cycle that defines intervals during which the antenna is sampled for presence of the RF signals (e.g., approximately 20 ns every 100 &mgr;s). A second embodiment of the RF transponder includes a wake-up circuit as in the first embodiment that is further adapted to detect a code sequence modulated in the RF signals. The code sequence is unique for a class of R…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.