A low-IF CMOS double quadrature mixer exhibiting 58 dB of image rejection for silicon TV tuners

To ease full integration of a TV-receiver, a low-IF architecture has been developed. To cancel the adjacent channel at the image of the mixer, a quadrature mixer can be used with a limited image rejection of about 40 dB, which is 10 dB below the target of more than 50 dB. Therefore, a low-IF passive CMOS double quadrature mixer has been implemented which achieves high dynamic range and more than 58 dB of image rejection over a wide frequency range. The image rejection is now limited by the mismatch in the mixers and the IF polyphase filter.