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Frequency conversion circuit

  • US 5,179,731 A
  • Filed: 06/08/1990
  • Issued: 01/12/1993
  • Est. Priority Date: 06/09/1989
  • Status: Expired due to Term
First Claim
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1. A circuit array for frequency translation of an input signal using the principle of quadrature signal processing, comprising:

  • first mixer means for mixing a first portion of the input signal with a first quadrature heterodyne signal;

    second mixer means for mixing a second portion of the input signal with a second quadrature heterodyne signal which is shifted 90°

    in phase with respect to the first quadrature heterodyne signal; and

    heterodyne signal generator means for generating the first and second quadrature heterodyne signals, the heterodyne signal generator means including a first portion which is connected to the first and second mixer means and a second portion which is connected to the first portion and which receives a local oscillator signal, the first portion of the heterodyne signal generator means having a first control loop means for stabilizing the 90°

    phase shift between the first and second quadrature heterodyne signals,wherein the second portion of the heterodyne signal generator means includes amplifier means for generating an amplified local oscillator signal, the amplified local oscillator signal having a keying ratio, and means for adjusting the keying ratio to 0.5, the means for adjusting having a second control loop which includes a symmetry detector, the amplified local oscillator signal being conveyed to the first portion of the heterodyne signal generator means.

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