Inverter : basic requirement for producing a complete range of Logic circuits




Basic Inverter: Transistor with source
connected to ground and a load resistor
connected from the drain to the positive
Supply rail

Output is taken from the drain and control
input connected between gate and ground

Resistors are not easily formed in silicon
they occupy too much area


NMOS Depletion Mode Transistor Pull - Up


Pull-Up is always on – Vgs = 0; depletion

With no current drawn from outputs, Ids
for both transistors is equal


NMOS Depletion Mode Inverter Characteristics


Dissipation is high since rail to rail current flows when Vin = Logical 1
Switching of Output from 1 to 0 begins when Vin exceeds Vt of pull down device
When switching the output from 1 to 0, the pull up device is non-saturated initially and this presents a lower resistance through which to charge