Inkjet-printed reflection amplifier for increased-range Backscatter radio

Building ultra large scale wireless sensor networks (WSNs) requires very low-power and low-cost sensor designs. Backscatter radio is a communication scheme that can accommodate for these two constraints, as opposed to active radio architectures. For large scale applications, backscatter communication range extension is a necessity; for this, careful tag design has to be employed, in order to minimize the tag information bit-error-rate (BER) at the reader. Conventional backscatter radio/RFID load modulators achieve reflection coefficients whose magnitude is less than unity; thus, the reflection coefficients´ difference magnitude-which is directly related to the backscatter signal-to-noise ratio (SNR)-is upper bounded by |ΔΓ| ≤ 2. This is a limitation for SNR maximization, and alternative system architectures have to be exploited for load modulators. In this work, an architecture is presented that overcomes this limitation with the use of a low-power reflection amplifier, which shows a reflection coefficient greater than unity on its port. The amplify-and-reflect system proposed can be utilized to significantly increase the SNR of the backscattered signals and the uplink range of RF tags.