[moved] NMOS amplifier design, parameters given

[Mohammed Abrar]

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.

 

[Audioguru]

Re: NMOS amplifier design, parameters given

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

 

[Mohammed Abrar]

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

 

[Audioguru]

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?

 

[Tahmid]

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

 

[Audioguru]

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.

 

[Tahmid]

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.

 

[Audioguru]

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