| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a frequency detection circuit capable of accurately detecting the frequency of a detection target signal without using any A/D converter having high voltage resolution. <P>SOLUTION: The frequency detection circuit includes a mixer 3 for mixing an RF signal which is a detection target signal with an LO signal oscillated by a local signal source 2 to output an IF signal, having a frequency ¾F_rf-F lo¾ equivalent to a frequency difference between the RF signal and the LO signal among IF signals of frequency ¾F_rf ±F_Lo¾ output from the mixer 3, and a low-pass filter 4 for passing only an IF signal (IFL signal) having its frequency lower than that F_rf of the RF signal. <P>COPYRIGHT: (C)2013,JPO&INPIT |
