A Very Low Offset 1.9-GHz Si Mixer For Direct Conversion Receivers

Abstract

A direct conversion receiver (DCR) is a candidate for realizing a small size and low cost wireless terminal because IF filters can be eliminated. However, the DCR suffers from dc offset and 2nd order distortion generated mainly in the direct conversion mixer. A dc offset canceler has been proposed to compensate for this unavoidable dc offset [l], and it must be within 10 mV at the output of the mixer considering hardware complexity of the dc offset canceler. This paper presents an approach to substantially reduce dc offset and 2nd order distortion in the mixer for the DCR.