A passive mixer-first receiver with negative feedback for impedance matching

A passive mixer-first receiver with negative feedback to adjust the input impedance is introduced in this paper. By adding a frequency translational negative feedback from baseband output to RF input, the proposed receiver can be matched well around the LO frequency. The current mode passive mixer-first receiver with negative feedback is designed in a 0.18 μm CMOS process. The prototype is functional from 1.26 to 1.31 GHz and achieves a 7.8 dB noise figure and a 12 dBm in-band IIP3. The feedback transforms the original unmatched input impedance to 50 Ω, which is appropriate for a RF system.