CMOS integrated low TX noise digital transmitter with tunable directional coupler for high performance UHF RFID reader

Abstract

A fully CMOS integrated low TX noise UHF RFID digital transmitter with tunable directional coupler is proposed. The transmitter decreases the AM noise density to −144.6 dBc/Hz at 10 kHz offset by eliminating noisy conventional analog components and optimizing LO chain. The tunable transformer‐based directional coupler which is feasible for CMOS integration exhibits high isolation performance of −55 dB over the entire band. The transmitter with quadrature DPA structure supports DSB/SSB/PR‐ASK modulation, and with the directional coupler, it achieves 22.8 dBm peak power with drain efficiency of 37.8%. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1750–1756, 2016