Feedback control

  • US 4,494,074 A
  • Filed: 04/28/1982
  • Issued: 01/15/1985
  • Est. Priority Date: 04/28/1982
  • Status: Expired due to Term
First Claim
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1. In a feedback control system for providing a controlled output signal in response to an input control signal having components including amplifying means having an input and output for amplifying a signal applied to said input and arranged in a closed loop with feedback means for coupling said output to said input and the amplifying means characterized by open loop gain and phase margin between said input and output when the feedback path therebetween is interrupted, the improvement comprising,means for establishing the open loop gain of said amplifying means substantially uniform at a significant level over a predetermined frequency range bounded substantially at at least one end by a break frequency,said amplifying means including means for establishing the change in said open loop gain as a function of frequency outside said predetermined frequency range in a region from said break frequency to a critical frequency where said open loop gain is substantially unity with magnitude of slope of said open loop gain greater than 6 decibels per octave for a significant portion of said region while maintaining the phase margin in said region sufficient to ensure stability,thereby providing high gain over said predetermined frequency range while avoiding oscillation and minimizing the error between said controlled output signal and a desired controlled output signal designated by said input control signal.

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