Receiving circuit

主要是在具有多个信道的数字调制方式的通信系统中，与接收电路有关，能够减少接收系统的功率、精简电路、减少消耗功率。借助于从本地频率信号发生电路4把与信道间中心值匹配的上、下频率分别提供到第一变频电路2和第二变频电路3上，可以产生分别按所需波、以及上侧信道和下侧信道这三个信号的两个输出信号；利用共同波提取电路5，把各变频电路2和3中共同存在的所需波提取出来；利用频率偏置电路6，把该输出中ω0的频率偏置消除；进而，利用滤波器8，把不需要的频率分量消除。还有，在共同波提取电路5中，利用变压器，借助于利用互感，至少可以使共同波与非共同波在电路内的差异、比过去增大一倍以上。 A receiving circuit mainly available in a digital modulation type communication system having a plurality of channels, which is capable of reducing power in a receiving system, simplifying the circuit and reducing the power consumption. Upside and downside frequencies corresponding to a central value between channels are separately supplied from a local frequency signal generating circuit 4 to first and second frequency converting circuits 2, 3 so that two output signals are developed with respect to one of a desired wave, upside channel and downside channel. The desired wave present in common in the first and second frequency converting circuits 2, 3 is extracted in a common wave extracting circuit 5, and a frequency offset of omega o existing in the output of the common wave extracting circuit 5 is removed a frequency offset circuit 6 and further an unnecessary frequency component is filtered by a filter 8. In addition, the common wave extracting circuit 5 has transformers and, using its inductances, raises the difference between the common wave and the non-common wave within the circuit to more than two times that of a prior art.