Low Ripple Envelope Detection for Load Modulated Communication in SWIPT

In this work we propose a new design methodology for envelope detectors in amplitude shift keyed communication. The method's premise is that a deliberately designed distortion can significantly improve the performance of a data receiver by reducing the bit error rate (BER). The main significance is in simultaneous wireless information and power transfer (SWIPT) applications where this envelope detector can be used to improve the recovery of messages transmitted from battery-less units employing load modulation. The key principle is the reduction of ripple voltage, which allows a battery-less unit to use a smaller modulation depth and thus remain in an impedance matched condition while receiving power and transmitting data simultaneously. A design criterion was developed to enable this improvement and implemented in a software-defined receiver (SDR). Data was transmitted through a wireless power transfer system designed for Qi purposes and recovered using the SDR, from which BER plots were produced and it was shown that the design indeed maximizes the performance.