A 4-GHz Active Scatterer in 130-nm CMOS for Phase Sweep Amplify-and-Forward

This article demonstrates the cooperative diversity improvement achieved using a 120- active scatterer built in 130-nm CMOS technology. The low-power all-analog device acts as a repeater, or relay, for phase sweep amplify-and-forward cooperative transmission. The device relies on microwave reflection to amplify, dynamically phase modulate, and reradiate the incident signal. This reduces the duration of the fades experienced in the indoor radio channel and improves error correction code performance. Radio channel propagation measurements collected using the relay prototype clearly show the effect of the phase modulation on fading and system level simulations conducted using the propagation data show a fivefold increase in coverage area.