| 摘要 |
PROBLEM TO BE SOLVED: To provide a receiver improved in interference wave suppression ratio at a frequency to which a particularly high interference wave suppression ratio is required.SOLUTION: The receiver includes: a gain variable amplifier 3 which receives an RF signal as an input and of which the gain is varied in accordance with a control signal; a frequency converter 4 for frequency-converting an output of the gain variable amplifier 3 into an intermediate frequency; a low-pass active filter 6 which receives an output of the frequency converter 4; a first circuit (DET1, Vref1, DIFFAMP1) for detecting the power of a node on a pre-stage of the active filter and generating a first signal for the gain control of the gain variable amplifier 3; a second circuit (DET2, Vref2, DIFFAMP2) for detecting the power of an intermediate node of the active filter and generating a second signal for the gain control of the gain variable amplifier 3; a comparator 14 for comparing magnitudes of the first and second signals; and a changeover switch 15 for selecting one of the first and second signals based on a result of the comparison and supplying the selected signal as a control signal for the gain control of the gain variable amplifier 3. |
