Patent ID: 8619925
Filing Date: 2013-12-31
Classification: H03F,H03G

Abstract:
1. An automatic gain control circuit comprising: a variable gain amplifier configured so that a gain is varied by a first control signal; a detector circuit to detect an intensity of an output signal of the variable gain amplifier; a comparator to compare an output signal of the detector circuit with a reference signal; an integrator to integrate a signal corresponding to an output signal of the comparator, and output an integration result to the variable gain amplifier as the first control signal; a loop gain control unit, connected between the comparator and the integrator, and configured so that a loop gain is varied by a second control signal, the loop gain control unit including a plurality of coefficient multipliers to multiply filter coefficients, different from each other, to the output signal of the comparator; a level detection unit to detect an intensity of an output signal of the integrator, and output a detection result to the loop gain control unit as the second control signal, the level detection unit including a highest bit detection unit to detect a position of a highest bit where a bit value of a digital output of the integrator becomes ‘1’, the loop gain control unit including a bit shifter to determine a shift amount based on the position of the highest bit, and shift the digital output of the comparator by the shift amount; and a selector to select the filter coefficient to multiply to the output signal of the comparator based on the detection result of the level detection unit.