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Phase modulator operated in saturation and with small angle modulation

  • US 5,126,698 A
  • Filed: 12/20/1990
  • Issued: 06/30/1992
  • Est. Priority Date: 06/02/1989
  • Status: Expired due to Fees
First Claim
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1. A phase modulator for providing a modulated carrier signal which is phase shifted by an angle relative to an input signal, comprising:

  • (a) a first and a second signal path for the input signal;

    (i) the two paths being such that the phase difference between the outputs of the first and second paths is substantially 90°

    ;

    (ii) wherein at least one of the two paths includes a mixer which responds to a modulating signal for selecting the polarity of the phase difference; and

    (iii) said mixer operating in saturation so that the amplitude of the angle is substantially independent of the amplitude of the modulating signal;

    (b) means for splitting the input signal and applying the split input signal to the two paths such that the amplitude of the input signal in said path having the mixer is at least 20 dB lower than the amplitude of the input signal in the other path; and

    (c) means for re-combining the outputs of the two paths forming a vector sum to provide a modulated carrier signal.

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