Patent ID: 6859190

Claim:
An apparatus, comprising; a passive radio frequency (RF) transponder (Tag), comprising; an antenna for receiving power and signals from an RF field, and for sending signals by backscattering power from the RF field; tag electronics connected to the antenna, the tag electronics contained in a single semiconductor chip, the tag electronics for receiving signals from the antenna and for controlling the antenna impedance for sending signals; a tag power supply in the single semiconductor chip for receiving RF power from the antenna, the tag power supply used as the sole power supply for the tag electronics; wherein the RF power is rectified in a diode rectifier circuit, and wherein the diode rectifier circuit comprises; at least a first diode rectifier stage for producing a DC voltage greater than the AC RF voltage produced in the antenna by the RF field, and; at least a second diode rectifier stage for producing a voltage greater than twice the AC RF voltage produced in the antenna by the RF field; wherein the parasitic capacitance of the second diode rectifier stage is less than 80% of the parasitic capacitance of the first diode rectifier stage.