08-16-2017, 09:00 PM
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