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# [moved] NMOS amplifier design, parameters given

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#### Mohammed Abrar

##### Junior Member level 1
How do I design an nmos circuit ( with no resistors) given that the drain to source current is 40 microamps and Vds is fixed at 1 V. Having a hard time figuring out whether I need to apply the formula for saturation or linear region.

Re: NMOS amplifier design, parameters given

It is not an amplifier since the drain-source current and voltage are fixed.

Re: NMOS amplifier design, parameters given

It is not an amplifier since the drain-source current and voltage are fixed.

Ok, but how do I design it. It is a very basic question I know

Re: NMOS amplifier design, parameters given

You gave no specifications for the amplifier.
Gain, supply voltage, load impedance and frequency?
Class-A, class-AB or class-D?
Its maximum allowed distortion?

Why are the current and voltage so low?

Re: NMOS amplifier design, parameters given

How do I design an nmos circuit ( with no resistors) given that the drain to source current is 40 microamps and Vds is fixed at 1 V. Having a hard time figuring out whether I need to apply the formula for saturation or linear region.

That sounds like some sort of an on-chip amp. Are the IDS and VDS (40µA and 1V respectively) for the operating bias point?

You need to figure out what topology to use based on the following requirements:
• Gain
• Input impedance
• Output impedance
• Bandwidth

The title of this thread says "amplifier" but an amplifier cannot amplify if its current and voltage are fixed.
With the fixed current and voltage then the Mosfet is simply a 1V/40uA= 25k ohms fixed resistor.

That could be the DC operating bias point - eg for a single stage amp. Applying an input signal can then allow amplification of the AC signal.

He said that Vds is fixed at 1V. No load was mentioned. It is a "circuit" but it has no resistors.

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