A Baseband Circuit For Wake-Up Receivers With Double-Mode Detection And Enhanced Sensitivity Robustness

This paper proposes a baseband circuit for wake-up receivers with double-mode detection and enhanced sensitivity robustness for use in the electronic toll collection system. A double-mode detection method, including amplitude detection and frequency detection, is proposed to reject interference and reduce false wake-ups. An improved closed-loop band-pass filter and a DC offset cancellation technique are also newly introduced to enhance the sensitivity robustness. The circuit is fabricated in TSMC 0.18 mu m 3.3 V CMOS technology with an area of 0.12 mm(2). Measurement results show that the sensitivity is-54.5 dBm with only a +/- 0.95 dBm variation from the 1.8 to 3.3 V power supply, and that the temperature variation of the sensitivity is +/- 1.4 dBm from-50 to 100 degrees C. The current consumption is 1.4 to 1.7 mu A under a 1.8 to 3.3 V power supply.