Method for modulating the impedance of an antenna circuit
US8896368B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 26, 2013 |
| Grant date | Nov 25, 2014 |
| Priority date | — |
| Expiry date | Nov 26, 2033 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06K19/0713
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
An electromagnetic transponder includes an antenna circuit, a load, and a charge pump transistor having a current path coupled between the antenna circuit and the load. During operation, a retromodulated signal is transmitted at a first level by biasing the charge pump transistor during a first time period such that an impedance of the antenna circuit has a first impedance value and current flows from the antenna circuit to the load. A retromodulated signal at a second level is transmitted by biasing the charge pump transistor during a second time period such that the impedance of the antenna circuit has a second impedance value different than the first impedance value and current flows from the antenna circuit to the load. The retromodulated signals are transmitted at the first and second levels in a sequence determined to transmit information from the electromagnetic transponder.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.