A low power (9 mW) highly-digitized 2.4 GHz receiver for sensor network applications (IEEE 802.15.4 LR-WPAN) is realized by a 0.18 mum CMOS process. We adopted a novel receiver architecture adding an intermediate frequency (IF) level detection scheme to a low-power complex fifth-order continuous-time (CT) bandpass SigmaDelta modulator in order to digitalize the receiver. By the continuous-time bandpass architecture, the proposed SigmaDelta modulator requires no additional anti-aliasing filter in front of the modulator. Using the IF detector, the achieved dynamic range (DR) of the overall system is 95 dB at a sampling rate of 64 MHz. This modulator has a bandwidth of 2 MHz centered at 2 MHz. The power consumption of this receiver is 9.0 mW with a 1.8 V power supply.