| 摘要 |
A variable gain amplifier with digital output is described. The amplifier is useful for but not limited to input range selection in chart recorders or other measuring instruments. To minimize the number of expensive presision resistors used in the gain selection network each selected range is approximated by switching. A software routine then adjusts the gain after digitizing to the correct value for the selected range. Both range switching and gain correction are controlled by a general purpose microprocessor which also is available for other duties in the instrument.
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