Radio Frequency Identification (RFID) is an electronic tagging technology that allows an object, place, or person to be automatically identified at a distance without a direct line-of-sight using a radio wave exchange. Applications include inventory tracking, prescription medication tracking and authentication, secure automobile keys, and access control for secure facilities. RFID is a major trend that provides fundamental shifts along several business vectors and is expected to be a major growth area in wireless electronics.

RFID Radio Circuit Design in CMOS

Ansoft's HFSS™, Nexxim® and Ansoft Designer® provide the computational power to accurately design all aspects of an RFID system. This paper describes a reference design with circuits and an antenna for a UHF RFID system. A new Class 2 (Gen 2) tag was designed, including the extremely low power integrated circuit integrated with an inexpensive printed antenna. Details on the design of the rectifier power regulator, demodulator, reset circuit, modulator, and antenna are highlighted. The paper includes a system-level software verification of the RFID tag system to determine proper voltage regulation and signal demodulation.

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Nexxim®
Nexxim® is an advanced, frequency- and time-domain circuit simulator for engineers designing the next generation of high- performance DigitalRF CMOS ICs, GaAs/SiGe RFICs, SIP/SOC packages, power delivery systems and gigabit computer and communication backplanes. Dynamic, parameterized co-simulation with HFSS™ and Ansoft Designer® enables Nexxim to combine transistor-level detail for complex and highly nonlinear circuits with full-wave S-parameter models of the interconnect to provide the most accurate simulation capability for signal-integrity analysis and RF design.

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Ansoft Designer® provides an integrated schematic and design management front-end for complex analog, RF and mixed-signal applications. By leveraging advanced electromagnetic field simulators dynamically linked to powerful circuit and system simulation, Ansoft Designer enables engineers to design, optimize, and validate component, circuit, and system performance long before building a prototype in hardware.

HFSS™
HFSS™ is the industry-standard software for S-parameter, Full-Wave SPICE™ extraction, and 3D electromagnetic field simulation of high-frequency and high-speed components. Engineers rely on the accuracy, capacity, and performance of HFSS to design on-chip embedded passives, IC packages, PCB interconnects, antennas, RF/microwave components, and biomedical devices.