PURPOSE: To provide circuit configuration suitable for making the digital waveform generator for correcting the tube surface of a CRT into an MOSIC.

CONSTITUTION: This digital waveform generator for correcting the tube surface of the CRT is provided with a PLL circuit 1, first integration circuit 4 and second integration circuit 8. The PLL circuit 1 multiplies a vertical synchronizing signal Vsync and outputs counter data. The first integration circuit 4 is composed of the loop of an adder 2 and a register 3, integrates these counter data and outputs parabolic waveform data. The second integration circuit 8 is composed of the loop of an adder 6 and a register 7, integrates the parabolic waveform data and outputs S-shaped waveform data. These PLL circuit 1, first integration circuit 4 and second integration circuit 8 or the like can be made into the MOSIC.