JPS6465992A - Digital convergence device - Google Patents

Abstract

PURPOSE:To completely eliminate the drift of an analog corrected waveform and to always improve convergence characteristics regardless of temperature change or time passage, by feeding back the change of the analog corrected waveform obtained after the conversion of a D/A converter to the side of the D/A converter. CONSTITUTION:During the non-existant period of a corrected data waveform signal, which is digitally stored in a memory 1, a reference signal is superimposed by a multiplexer 3. The superimposed reference signal is converted into an analog signal (the analog corrected waveform) together with the corrected date waveform signal by a D/A converter 5, and drives a CY through an analog circuit part. The amplitude and direct current bias value of the analog corrected waveform are changed by the temperature characteristics, etc., of the D/A converter 5 and the analog circuit part. Thus, only the reference signal part of the analog corrected waveform is sampled by an S/H circuit 12, and the difference between the separately prepared unchangeable reference signal, which does not change due to the temperature change, etc., and the analog corrected waveform is detected by a detecting circuit 15. Further, the analog corrected waveform is controlled so that the gain of the D/A converter 5 and the direct current bias value of the signal immediately after the output from the D/A converter may be restored to a normal value.