Patent ID: 6072335
Filing Date: 2000-06-06
Classification: G05F,H03K

Abstract:
An inverter circuit having an input for receiving a digital signal level and an output having a high or low value dependent on said input, which circuit comprises first transistor circuitry connected between a node and a voltage supply line, second transistor circuitry connected between said node and a ground line, said node being connected to the output and said input being connected to both said first transistor circuitry and to said second transistor circuitry and arranged to switch on selectively either said first or second transistor circuitry in dependence on said input and thereby pull said node towards said voltage supply line or towards ground, said second transistor circuitry including first and second parallel conducting paths between said node and the ground line, the first conducting path including a weak transistor of low current carrying capacity and said second conducting path comprising a strong transistor of larger current carrying capacity, control circuitry being connected to said strong transistor to switch off said strong transistor when said node has fallen to a voltage value close to said ground line, wherein said first transistor circuitry includes first and second parallel conducting paths between said node and the voltage supply line, the first conducting path including a weak transistor of low current carrying capacity and said second conducting path comprising a strong transistor of larger current carrying capacity.