Patent ID: 8847735

Claim:
A radio frequency identification (RFID) circuit comprising: an antenna network, including an antenna and an antenna interface coupled to the antenna, configured to transmit and receive radio frequency waves, wherein the antenna interface includes a first capacitor and a second capacitor, which are coupled in series with the antenna; and an integrated circuit including a first pin and a second pin coupled respectively to a first node and a second node of the second capacitor of the antenna interface and configured to operate as a reader and a tag in combination with the antenna network, and wherein the integrated circuit comprises amplifier means embedded in output current and output voltage negative feedback loops and is configured to provide an output admittance determined by a ratio of the current and voltage negative feedback signals, at least when the RFID operates as a reader, such that a frequency response of the combined integrated circuit and antenna network is adjustable to selective characteristics without increasing power consumption of the RFID when operating as a reader.