A 5.8 GHz 54 Mb/s Backscatter Modulator for WLAN with Symbol Pre-Distortion and Transmit Pulse Shaping

This letter discusses the implementation of microwave backscatter links in CMOS technology which are similar to existing systems at mid-UHF for RFID, but intended for use at the 5.8 GHz ISM band for supporting future low-power WLAN applications. In order for backscatter links to operate in highly channelized environments we introduce a pulse-shaping technique to reduce out-of-band emissions as well as a symbol pre-distortion technique to improve the constellation spacing. Both techniques are introduced into a 65 nm prototype backscatter modulator chip and are shown to operate with QPSK modulation at 54 Mb/s (typical of WLAN standards). The backscatter modulator chip was shown to consume 1.61 mW of power.