A down conversion mixer is essentially used in a heterodyne wireless receiver to enhance the selectivity of the mixer. Down conversion mixer converts high frequency RF signal to low frequency IF signal before demodulation process. Being a nonlinear system, RF mixer dominates the overall performance of the system. Design of down conversion mixer is the most challenging part in a receive chain. Wideband impedance matching always remains a challenge in any radio frequency integrated circuit design. This paper presents the design of passive down conversion ring mixer with high linearity, broad band impedance matching without DC bias using differential resistive impedance matching. Proposed mixer is tuned for RF frequency of 3.432 GHz of band 1 of multi band orthogonal frequency division multiplexing (MB- OFDM) ultra wideband (UWB) system. Mixer core is based on FET Ring mixer topology. Mixer is simulated using Keysight Advanced Design (ADS) software with 180 nm CMOS process. The mixer achieves the minimum conversion loss of 10.49 dB, 1 dB compression point (P1dB) of 12.40 dBm, the Third Order Input Intercept Point (IIP3) of 12.010 dBm, a minimum Single Side Band (SSB) noise figure of 8.993 dB and S11 of less than -10 dB over frequency range covering 0 to 13.61 GHz. Layout of the mixer records an active area of 183.75 um2.