| 摘要 |
<p>A portable telephone provided with a receiving circuit of direct conversion type has a passive low-pass filter (32) for filtering the interference waves of the channels other than the channel of concern and its adjacent channel interposed between an I-channel mixer (28) and a baseband circuit (36) and a passive low-pass filter (34) for filtering the interference waves of the channels other than the channel of concern and its adjacent channel interposed between a Q-channel mixer (30) and a baseband circuit (36). These low-pass filters (32, 34) are of differential type, so that their circuit scales are small and have low power consumptions. The interference waves are filtered by the passive low-pass filters (32, 34) and active low-pass filters (56, 58), so that only desired channels can be reliably received.</p> |
