| 摘要 |
PURPOSE:To attain high speed control by retrieving an object satisfying conditions while narrowing the checked range by a 1/2 and further 1/2 in controlling the circuit gain with a digital control signal in response to the amplitude of an input signal. CONSTITUTION:A variable gain circuit 2 is provided, which has a switch selecting a gain among ordered gain in a larger order by the control signal. The amplitude of an output signal of the variable gain circuit 2 and a reference input 5 are compared by an amplitude comparison circuit 4 and a command of addition/subtraction is outputted based on the result and the rule of ordering. Then every time the gain is revised by an addition/subtraction circuit 6, the change in the order of the gain revised before is divided by two, a fraction is rounded off or truncated or rounded by a 1/2 circuit, and the amplitude of the output signal obtained by the gain of the order revised by the number obtained at the 1/2 circuit 7 to the order of the gain before the revision by the command of the amplitude comparison circuit 4 approaches the reference input 5 by addition or subtraction. A gain switching circuit 8revising the control signal controlling the switch so as to select the gain of the order obtained by the addition/subtraction circuit 6 is provided.
|
