RF tag front-end design for uncompromised communication and harvesting

Typically, low-cost and low-power backscatter radio communicators utilize a switching mechanism for alternating the antenna load between two values. In this way, they achieve modulation by reflection of the RF waves induced at the communicator´s antenna. For tags that employ a rectifier for wireless energy harvesting, a single transistor may switch between the matched harvester and a reflective load (an open or short). However, optimized backscatter communication occurs when switching between two reflective loads, ideally an open and a short. This prohibits the use of a harvester that requires a good matching (i.e. no reflections) and produces a tradeoff of either compromising communication performance or not employing a harvester. Although this may not pose a problem for commodity RFID tags that operate in short ranges and do not require high computational ability, it is a strong limitation for applications like wireless sensor networks that employ backscatter radio as a low-cost and low-power communication scheme. In this work, an RF front-end is designed, analyzed, and implemented, that overcomes the limitation of compromising communication performance when employing a harvester.