| 摘要 |
PURPOSE:To decrease current driving ability and to decrease noises generated in a power source of GND in an output circuit, by making the channel length of an MOSFET constituting a front stage circuit for output larger than the channel length of an MOSFET constituting other circuits. CONSTITUTION:An input waveform from 'L' to 'H' or from 'H' to 'L' is applied to an input terminal of a front stage circuit 1a of an output. Then, a parasitic capacitor 3 formed between the circuit 1a and an output circuit 2a is charged and discharged. The input waveform from 'H' to 'L' or from 'L' to 'H' is imparted to an input terminal of the output circuit 3a. At this time, when the channel lengths of a P-MOST and N-MOST constituting the circuit 1a are made long, current driving ability for the P- and N-MOSTs is decreased, and the input waveform of the output circuit 2a becomes gentle. Therefore, the charge and discharge times of the a parasitic capacitor 6 at the output terminal becomes long. Electromotive forces generated in parasitic inductances 10-12 of a GND line are suppressed. Noises generated in the GND 5 can be reduced. Similarly, noises generated in power source lines can be reduced. |
