A 6-10-GHz broadband down-conversion mixer fabricated in the 0.18-μm CMOS process for DS-UWB receivers is presented. The link budget of the DS-UWB receiver under 4-BOK or BPSK modulation is considered. The single-port design for the RF, LO and IF ports of the mixer can provide the advantage to reduce the complexity of measurement. The broadband mixer only needs a low LO power of -4 dBm (excluding the PCB loss) at 8 GHz. The mixer exhibits a DSB average conversion gain of 8 dB (without the output balun), a DSB average noise figure of about 13.5 dB, maximum input P1dB of -4 dBm, LO-RF and RF-LO isolation of 29-39 dB, and the current consumption of 10.5 mA (without the output balun) from a 1.5-V supply.