| 摘要 |
PROBLEM TO BE SOLVED: To provide a control method and an apparatus, capable of implementing high-speed gain switching to a multi-stage programmable gain amplifier (PGA), without the need for a high-resolution A/D converter. SOLUTION: The gain control method for a multi-stage PGA is a control method, in which an input level is detected for all PGAs, an optimal gain is calculated for each PGA based on the detected result, the determined (calculated) optimal gain value is set for each PGA at a time, and the method can conduct fast gain switching. A gain control apparatus of a multi-stage PGA for implementing the gain control method employs a configuration, in which the output of peak hold circuits PH1-PH3 holding the input level of PGAs 601, 603 and 605 is detected sequentially by an A/D converter 610 through sequential switchings of a switch group 609, an optimal gain for each PGA is calculated from the detected result by a computation circuit 6, and the determined optimal gain value is simultaneously set for each PGA. COPYRIGHT: (C)2004,JPO
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