| 摘要 |
<p>PURPOSE: To remarkably make the scale of a circuit small by forming binary data indicating the magnitude of an actual reproducing signal with respect to plural prescribed values indicating plural amplitudes which the reproducing signal has to take. CONSTITUTION: Outputs of comparators 301, 302 are also supplied to a data selector 306 and one of values 2A, 0, -2A is selected according to a reproducing signal level and an selected data is subtracted from an inputted 8-bit data in a subtracter. At this time, when a variable resistor of an AGC circuit is adjusted so as to make A32, values (+2A, 0, -2A) of detected data become respectively (+64, 0, -64) and the MSD of a result obtained by subtracting one of these values from an original data becomes a 3rd bit by counting from the MSD of the 8-bit data inputted in a terminal 300. Thus, a satisfactory tracking control is realized with a circuit constitution having an extremely small scale by similarly using the 3rd bit from the MSD of the output of an A/D converter.</p> |
