PURPOSE: To ensure the waveform shaping with no preshoot nor overshoot by multiplying the primary differential output and the secondary differential output of the video signal to correct the secondary differential output waveform and then making the peak value of the waveforms approximate to each other with the positive and negative polarity pulses.

CONSTITUTION: The narrow-band video signal SA is applied to differentiating circuit 2 and 3 to obtain primary differential output SB and secondary differential output SC and then to supply them to multipliers 4∼6 in sequence. The peak positions of signal SD and SE drift more inside than the peak position of the rise pulse of SC with a waveform sharpened. At the same time, the peak position of SD shifts inward for signal SF and SG as well, and signal SH and SI also show the similar trend to SE. Composite output SJ, SK and SL are obtained through the subtraction and addition via compounders 7∼9 with SL added 10 to SA to sharpen the both rise and fall. Thus, video shgnal SM featuring a wide band virtually is extracted.