A Differential FM Detector for Low-IF Radios

Binary differential detection of FM has drawn a lot of attention in the past. However, those receivers all apply a super heterodyne front-end architecture which first moves the received signal to an intermediate frequency. Fully integration of these receivers is not possible as the image-reject and channel selection filters will be off chip. Low-IF receiver architectures on the other hand enable low-cost, fully integrated implementations while they avoid common direct conversation problems. The "Low-IF" frequency in these receivers, however, makes them unsuitable for differential detection of binary FM as descrbed in the papers mentioned above. We, therefore, propose a new differential detector structure which is applicable in Low-IF receivers.