A highly-merged 2.4/5.7-GHz dual-band low-IF downconverter is demonstrated using O.18-μm CMOS technology. Weaver and Hartley architectures are utilized to achieve high image-rejection ratio (lRR) of first and second image signals. The first LO (LO1) is set exactly halfway between the two bands. That is, the 2.4/5.7-GHz bands are the first image signal of each other. However, in a real home/commercial environment, a 5.7/2.4-GHz blocking signal is present when the 2.4/5.7-GHz band is desired and degrades the dynamic range of the receiver. Therefore, the dynamic range degradation due to the co-existence of RF and image signals is discussed in this paper.