James E Atherton

US Patent:

8395505, Mar 12, 2013

Filed:

Apr 7, 2009

Appl. No.:

12/420009

Inventors:

Mark Alfred Hadley - Newark CA, US
James Harold Atherton - Morgan Hill CA, US
Jay Tu - Pleasanton CA, US
Edward John Boling - Fremont CA, US
John Stephen Smith - San Jose CA, US

Assignee:

Alien Technology Corporation - Morgan Hill CA

International Classification:

G08B 13/14

US Classification:

3405721, 340 101, 3406362, 340658

Abstract:

Methods and apparatuses for selecting a subset of RFID tags are provided in some embodiments. These methods and apparatuses utilize the susceptibility to light by persistent nodes found in passive tags. Light can be used to intentionally reduce persistence times in a particular subset tags or even an individual tag. Then, persistent nodes can be used as a selection criterion to distinguish previously illuminated tags from non-illuminated tags. In other embodiments, a power circuit receives a RF input source and generates a direct current (DC) output voltage. The circuit includes a bias circuit to supply a gate to source bias, which is independent of the DC output voltage. The circuit further includes a voltage multiplier circuit that is coupled to the bias circuit. The voltage multiplier circuit has MOS transistors with one transistor to receive the gate to source bias.