| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a FSK detection circuit capable of minimizing a change in an FSK detection output level by applying an AFC signal to an LC parallel resonance circuit 14 and connecting a level compensation varactor element 15(3) with the AFC signal applied thereto to a 90-degree phase shift circuit 15. <P>SOLUTION: The FSK detection circuit includes: a multiplier circuit 13 between first and second input terminals of which the 90-degree phase shift circuit 15 is connected, to the first input terminal of which an FSK modulation signal is given, and to the second input terminal of which the FSK modulation signal whose phase is shifted by 90 degrees via the 90-degree phase shift circuit 15 is applied; and the LC parallel resonance circuit 14 connected to the second input terminal and comprising parallel connection of a ceramic discriminator 14(1) and a varactor diode 14(3) with the AFC signal applied thereto, and a parallel connection circuit comprising a level compression varactor diode 15(3) with the AFC signal applied thereto and a capacitor 15(4) is connected to the 90-degree phase shift circuit 15. <P>COPYRIGHT: (C)2006,JPO&NCIPI</p> |
