This paper first provides a result of the double-quadrature image rejection mixer using the polyphase filter in the 5-GHz wireless LAN. The double-quadrature image rejection mixer uses four mixers with both RF and LO inputs in the quadrature phases. All quadrature signals for both RF and LO inputs are generated from the polyphase filter.
This double-quadrature image rejection is designed based on the dual-conversion architecture receiver. For the high image rejection in the high frequency, the double- quadrature topology is adopted instead of the single-quadrature topology, with high the narrow band filtering effect by the IF frequency (1GHz). Two-transconductance stages in the double-quadrature mixer are shared by a pair of I/Q switching stages respectively to reduce the mismatch from the conversion gain in the mixers. The high frequency unwanted harmonics components generated after first down conversion process is reduced through the IF amplifiers for the linearity of the receiver.
This work i s implemented based on 0.18-$\mum$ CMOS technology and shows the image rejection of the 30-35 dB from only the double-quadrature image rejection mixer block and power gain of -9dB. The input-referred IP3 is +9dBm with input ldB compression point of-2dBm. It consumes 60mA total current from a 1.8V supply.