| 摘要 |
PURPOSE:To attain self-calibration of a D/A converting circuit so as not to make unnatural interruption of audio output to the users, by using an operating time of the operation switch and non-signal time of inter-musics and calibrating the self-calibrating type D/A converter at any time. CONSTITUTION:A control circuit 20 generates a pulse instantly when an operation key 21 is depressed. A demodultor 16 detects no sound groove being inter- musics and generates a prescribed pulses during this period. Further, in a logical sum circuit 19 ORs an output pulse from a control circuit 20 and a pulse representing the inter-musics from the circuit 16 and the OR output is given to a correction mode signal input terminal of the D/A converter 17. Thus, the calibration of the conversion circuit is done during the inter-musics or when the operation key is depressed. |
