US 7,321,801 B2
Automatic gain adjustment device and automatic gain adjustment method
Yasushi Saito, Saitama (Japan)
Assigned to Sony Corporation, (Japan)
Filed on Mar. 30, 2004, as Appl. No. 10/813,454.
Claims priority of application No. P2003-098480 (JP), filed on Apr. 01, 2003.
Prior Publication US 2004/0199271 A1, Oct. 07, 2004
Int. Cl. G05B 13/02 (2006.01); H03L 7/06 (2006.01); H03D 3/24 (2006.01)
U.S. Cl. 700—37  [327/147; 327/156; 375/373] 4 Claims
OG exemplary drawing
 
1. An automatic gain adjustment device of a feedback control system that uses a phase difference between an output signal obtained from a controlled object and an input signal while controlling the object based on the input signal, the automatic gain adjustment device comprising:
a disturbance generator for generating the input signal; the input signal being a sine wave of a predetermined frequency;
phase shifting means connected to an input stage of the feedback control system for shifting a phase of the input signal such that a phase shift amount of the phase shifting means is set so that a frequency of the input signal to be supplied to a closed loop coincides with a crossover frequency at which an open loop gain of the feedback control system becomes 0 db;
a band-pass filter for filtering the output signal to extract a component signal of the predetermined frequency;
a multiplier for multiplying the phase-shifted input signal from the phase shifting means and the component signal from the band-pass filter;
an integrator for integrating product results of the multiplier over one cycle at the predetermined frequency and outputting integrated product results; and
a gain setting unit for adjusting a gain of the feedback control system based on a sign of the integrated product results from the integrator so that the open loop gain converges to 0 dB.