| 摘要 |
A distortionless receiving circuit used in a radio receiver to reduce degradation of the receiving sensitivity in case of a relatively lower receiving electric field. The circuit has a radio frequency amplifier, a mixer for frequency conversion, a variable attenuator interposed between the radio frequency amplifier and the mixer, an intermediate frequency amplifier disposed on the output side of the mixer, a detector and a control block. The control block generates a control signal in accordance with the intensity of the output signal of the intermeddle frequency amplifier. The attenuation amount of the variable attenuator is controlled by the control signal in a stepwise manner.
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