| 摘要 |
PURPOSE:To reduce an error at a zerocrossing point without trimming by varying a bipolar current source of a D/A converter and controlling the current source so that analog values of test signals are made to zero. CONSTITUTION:The D/A converter 5b to be a correcting current source is switched to two current values by switching data of counters 17, 18 through a selector 19 and one current value is controlled so that a current added value for digital data 011-1 is made to one bit and a current added value for 100-0 is close to zero. Consequently, a conversion error for an analog amplitude zero point is reduced, listening distortion is reduced and trimming can be omitted. |
