An Ultra Low Power Diode (ULPD) load based down conversion mixer is presented in this paper. The mixer is designed to operate at 2.5 GHz RF frequency with 250MHz Intermediate frequency. The conversion gain provided by the mixer is maximum ~8dB at 2.1GHz RF frequency. The power consumption for the mixer core circuit is ~17mW. The mixer presents good RF to IF port isolation with input return loss less than zero. The Input Third Order Intercept increases from ~9dBm to 15.8 dBm for variation of the source degeneration inductors from 1 nH to 20 nH. The IIP3 is 11.64dBm at 4 GHz RF frequency with 1nH inductor. The mixer is simulated with 1.8V voltage supply using 180nm CMOS process. The RF power is -30dBm and LO power is set to 5dBm.