| 摘要 |
PURPOSE:To make a write level to a magnetic tape equal to each other by setting a changing ratio when a current is increased equal to a changing ratio when a current is decreased. CONSTITUTION:When an input signal impressed to a terminal IN is changed from H to L and the ON resistance of a P-channel FETP11 is set to be greatly smaller than R11, the gate potential of an N-channel FETN12 is calculated as specified, and the changing ratio in the current I flowing to the FETN12 is controlled optionally by selecting optionally a capacitance element C11 and resistance elements R11, R12. The maximum value (dI/dt)r.max of the changing ratio when the current I is increased and the maximum value (dI/dt)f.max of the changing ratio when the current I is decreased are calculated as specified respectively by using betap, VCC and an absolute value Vrp. In order to make the maximum changing ratio when the current I is increased equal to the maximum changing ratio when the current I is decreased the resistance of the resistors R11, R12 is set so as to satisfy 4VCC.R12=(R11+R12) (VCC-¦VTP¦). In this case, the positive and negative detection levels of the current driving circuit are the identical to each other and the positive and negative noise margins are equal and the operation is made stable. |
