Patent ID: 9030297
Filing Date: 2015-05-12
Classification: G06K,H03C

Abstract:
1. A full-duplex RF tag for sending data to a tag reader by load modulation of an RF field of said tag reader, the tag comprising: an antenna to couple to said RF field of said tag reader; a resonant circuit coupled to said antenna to resonate at a frequency of said RF field with a resonance amplitude; a local power store to store power extracted from said RF field; a modulation system to provide said load modulation by modulating one or both of said resonance amplitude and a relative phase of a signal in said resonant circuit with respect to said RF field; and a feedback circuit coupled to said resonant circuit and to said local power store to control one or both of said resonance amplitude and said relative phase to control transients in said resonance amplitude caused by said modulating to provide said load modulation, wherein said feedback circuit is arranged to draw power from the resonant circuit and store the drawn power in said local power store during said load modulation, said drawing of power to control a first modulation transition of said resonance, and is further arranged to draw power from said local power store during said load modulation to control a second, opposite-going modulation transition of said resonance, wherein said first and second modulation transitions are for said load modulation and are each between two data states of said modulating.