Chip Impedance Evaluation Method for UHF RFID Transponder ICs over Absorbed Input Power

Based on a de‐embedding technique, a new method is proposed which is capable of evaluating chip impedance behavior over absorbed power in flip‐chip bonded UHF radio frequency identification transponder ICs. For the de‐embedding, four compact co‐planar test fixtures, an equivalent circuit for the fixtures, and a parameter extraction procedure for the circuit are developed. The fixtures are designed such that the chip can absorb as much power as possible from a power source without radiating appreciable power. Experimental results show that the proposed modeling method is accurate and produces reliable chip impedance values related with absorbed power.