Patent ID: 6965656

Claim:
An automatic gain control method comprising: a frequency conversion process for converting a high frequency signal applied via an input terminal to an intermediate frequency signal; a first gain control process for controlling a gain of the high frequency signal; a second gain control process for controlling a gain of the intermediate frequency signal; a gain determination process for determining the gains in the first and the second gain control processes based on the intermediate frequency signal after gain control, so that a signal level of the intermediate frequency signal becomes a predetermined value; a level detection process for detecting signal levels at a plurality of points on a signal path ranging from after the gain of the high frequency signal is controlled in the first gain control process to before the gain of the intermediate frequency signal is controlled in the second gain control process; and a third gain control process for controlling a signal level in the signal path, so that a difference between the signal levels detected in the level detection process becomes a predetermined constant value.