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Frequency-converter

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Frequency converter

Details

Inventors: Shibata, Fumiaki; Matsutake, Masayuki;
Assignee: Kabushiki Kaisha Toshiba (Kanagawa, JP)
Primary Examiner: Griffin; Robert L.
Assistant Examiner: Kuntz; Curtis
Attorney, Agent or Firm: Finnegan, Henderson, Farabow, Garrett, & Dunner

A frequency converter suitable for a multi-channel broadcast signals receiver is provided. The frequency converter includes a pre-amplifier with an AGC control terminal, first and second local oscillators, a first mixer for converting a first-RF frequency of the broadcast signal to a second-RF frequency using a first oscillation signal output from the first local oscillator, a second-RF signal amplifier with an AGC control terminal for amplifying the second-RF signal, a second mixer for converting the second-RF frequency of the second-RF signal output from the second-RF signal amplifier to a third-RF frequency using a second local oscillation signal output from the second local oscillator, and an AGC circuit for feeding back to the pre-amplifier and the second-RF signal amplifier the AGC signal which is obtained from the third-RF frequency signal as a conversion output from the second mixer for simultaneously controlling the gains of both the preamplifier and the second-RF signal amplifier.

DETAILED DESCRIPTION An object of the present invention is to provide a frequency converter which can control the signal level at an optimum value suitable for both the C/N characteristic and the signal distortion characteristic.
These and other objects are achieved in a frequency converter which includes an input terminal for receiving a broadcast signal with a first frequency, a first variable gain amplifier for amplifying the broadcast signal applied from the input terminal, a local oscillator for generating a local oscillation signal, a frequency mixer circuit for converting the broadcast signal applied from the first amplifier to a second frequency using the local oscillation signal output from the local oscillator, a second variable gain amplifier for amplifying a signal with the second frequency applied from the frequency mixer circuit and an AGC circuit means for feeding back to the first and second variable gain amplifiers an AGC signal which is obtained from a signal output from the second variable gain amplifier.
Additional objects, advantages and features of the present invention will become apparent to persons skilled in the art from a study of the following description and of the accompanying drawings, in which:

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