| 摘要 |
PURPOSE:To eliminate simultaneous change switching noise and ringing noise with a simple circuit constitution by generating a pulse with a prescribed phase relation to an input signal of a buffer of MOS inverter constitution and varying a threshold value of an inverter. CONSTITUTION:An input signal VIN is given to an input buffer 4 of a CMOS inverter and outputted from an output buffer 7 of similar constitution, and an NMOS transistor(TR) 22 of a noise suppression circuit 21 is connected between the buffers 4, 7. A Q output being a pulse with a width of a prescribed period from the leading of the signal VIN given to a D FF23 forming a monostable multivibrator circuit 25 receiving a leading operation waveform A at its clock terminal and reset via a delay circuit 24 is applied to the base of the TR 22. Then the TR 22 connecting to a low voltage power supply VSS is turned on, the threshold level of the inverter 4 is lowered to eliminate noise substantially and the simultaneous change switching noise and ringing noise are eliminated with the simple circuit constitution. |
