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How do you increase the gain or steepness in the Vout vs Vin curve of cmos inverter?

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iVenky

iVenky

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How does the steepness of the Vout vs Vin curve (i.e gain in the middle region) of the CMOS inverter depend on the W/L of the transistor?

Will the gain/steepness increase if you decrease W/L ?

Thanks a lot...
 

One way to increase the steepness is by producing the thermal stress on the inverter. This will make the slope in the middle steeper by reducing Vt but it will also distort the symmetry of the transfer characteristic.

The proper way therefore would be to have the VIL and VIH values need to be as close to VM as possible. Apart from depending on VDD and Vt, these values also depend on 'r', which depends on kn and kp.

So I would say that yes, the steepness of the curve does depend on the \[\frac{W}{N}\] values of the CMOS inverter. To check how, simply focus on the line of relationships I mentioned above and cross-reference them with the actual formulas. I'm sure you'll be able to figure it out.
 
Last edited:

hshah8970 said:
One way to increase the steepness is by producing the thermal stress on the inverter. This will make the slope in the middle steeper by reducing Vt but it will also distort the symmetry of the transfer characteristic.

The proper way therefore would be to have the VIL and VIH values need to be as close to VM as possible. Apart from depending on VDD and Vt, these values also depend on 'r', which depends on kn and kp.

So I would say that yes, the steepness of the curve does depend on the \[\frac{W}{N}\] values of the CMOS inverter. To check how, simply focus on the line of relationships I mentioned above and cross-reference them with the actual formulas. I'm sure you'll be able to figure it out.
Click to expand...

I have found out. The gain decreases with increase in current at Vin=Vm. (i.e.) as the W/L ratio increases the gain decreases/ steepness is reduced.
 

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