Power Conversion Gain as a design metric for RFID systems

This paper presents a novel method for determining the power available to a passive radio-frequency identification (RFID) tag, the Power Conversion Gain (PCG). The power conversion gain of a tag combines the tag´s antenna pattern with its charge pump efficiency to give the system designer the tag´s output power as a function of angle and maximum received input power. This metric is more useful for system designers because it helps to determine the tag´s sensitivity to orientation which is exaggerated by the non-linearity of the charge pump. This paper demonstrates the use of PCG using measured results from a 4-stage Dickson charge pump operating at 5.8 GHz and a directional antenna as a worst case scenario.