Problem 2 b - minimum Vout of inverter

[Aaron Staley]

This sub-problem is confusing me. It asks for the minimum value of the
inverter, but then asks how to lower it.

Is the equation Ioutsatd = kd*(Vin - Vtd)*VoutSadD legal here? As it
is, vin can be raised to infinity, resulting in a triode range slope of
infinity (starting at 0), leading to the load line operating at 0 V -
and thus resulting in a vout that can't possibly be lowered by changing Rd.


So is another equation supposed to be used to determine the minimum?

[Bharath]

Think about the effect of the resistor. That is, can you change the
resistor value to lower the minimum output from the inverter?

Bart

Post by Aaron Staley
This sub-problem is confusing me. It asks for the minimum value of the
inverter, but then asks how to lower it.
Is the equation Ioutsatd = kd*(Vin - Vtd)*VoutSadD legal here? As it is, vin
can be raised to infinity, resulting in a triode range slope of infinity
(starting at 0), leading to the load line operating at 0 V - and thus
resulting in a vout that can't possibly be lowered by changing Rd.
So is another equation supposed to be used to determine the minimum?

[Aaron Staley]

Increasing the resistance, leads to a reduced y-intercept on the
load-line a a reduced negative slope.

So yes, changing the resistance will change the output for a given vin.

But with our model, we can let vin be infinity (the minimum vout). And
at this point, changing the resistance has no effect on vout.

Is this question asking for the minimum vout for a given set of vins or
for all vins? (I am interpretted the question as asking the latter)

-Aaron

Post by Bharath
Think about the effect of the resistor. That is, can you change the
resistor value to lower the minimum output from the inverter?
Bart

Post by Aaron Staley
This sub-problem is confusing me. It asks for the minimum value of
the inverter, but then asks how to lower it.
Is the equation Ioutsatd = kd*(Vin - Vtd)*VoutSadD legal here? As it
is, vin can be raised to infinity, resulting in a triode range slope
of infinity (starting at 0), leading to the load line operating at 0 V
- and thus resulting in a vout that can't possibly be lowered by
changing Rd.
So is another equation supposed to be used to determine the minimum?

[Philip Godoy]

You should only do Vin=0V to Vin=3V, since those are the supply voltages.

Sorry about the confusion.

-Philip

Increasing the resistance, leads to a reduced y-intercept on the load-line
a a reduced negative slope.
So yes, changing the resistance will change the output for a given vin.
But with our model, we can let vin be infinity (the minimum vout). And at
this point, changing the resistance has no effect on vout.
Is this question asking for the minimum vout for a given set of vins or
for all vins? (I am interpretted the question as asking the latter)
-Aaron

Post by Bharath
Think about the effect of the resistor. That is, can you change the
resistor value to lower the minimum output from the inverter?
Bart

Post by Aaron Staley
This sub-problem is confusing me. It asks for the minimum value of the
inverter, but then asks how to lower it.
Is the equation Ioutsatd = kd*(Vin - Vtd)*VoutSadD legal here? As it
is, vin can be raised to infinity, resulting in a triode range slope of
infinity (starting at 0), leading to the load line operating at 0 V -
and thus resulting in a vout that can't possibly be lowered by changing Rd.
So is another equation supposed to be used to determine the minimum?

[Bharath]

In reality, can you have a circuit that accepts an infinite voltage as
input?

Bart

Increasing the resistance, leads to a reduced y-intercept on the load-line a
a reduced negative slope.
So yes, changing the resistance will change the output for a given vin.
But with our model, we can let vin be infinity (the minimum vout). And at
this point, changing the resistance has no effect on vout.
Is this question asking for the minimum vout for a given set of vins or for
all vins? (I am interpretted the question as asking the latter)
-Aaron

Post by Bharath
Think about the effect of the resistor. That is, can you change the
resistor value to lower the minimum output from the inverter?
Bart

Post by Aaron Staley
This sub-problem is confusing me. It asks for the minimum value of the
inverter, but then asks how to lower it.
Is the equation Ioutsatd = kd*(Vin - Vtd)*VoutSadD legal here? As it is,
vin can be raised to infinity, resulting in a triode range slope of
infinity (starting at 0), leading to the load line operating at 0 V - and
thus resulting in a vout that can't possibly be lowered by changing Rd.
So is another equation supposed to be used to determine the minimum?