| 摘要 |
A volume control circuit comprises a variable gain stage (306), having a variable gain, and an up/down counter (324) for counting. The counter (324) has a counter input (321) and a counter output (333) for providing a first word (333) for controlling the gain of the gain stage. A microprocessor interface (326) includes an interface output (323) for providing a second word. A digital magnitude comparator (333) compares the first (323) and second (333) words. The comparator having a first input (333) connected to the counter output, a second input connected to the interface output (323), and a comparator output connected to the counter input (321), provides a count signal (329) if the words do not match and for providing a non-count signal (329) if the words match. Thus, responsive to the count signal (329), the up/down counter (324), counts from the first word, in a direction approaching the second word by a least significant bit to form a new first word, for controlling the gain of the gain stage.
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