explain why ideal mosfets are referred to as square law devices in one or two sentences 28795

Name: explain why ideal mosfets are referred to as square law devices in one or two sentences 28795
Uploaded: 2023-05-16T01:52:27-08:00
Duration: 6 min 47 s
Channel: Supreeta N
Description: explain why ideal mosfets are referred to as square law devices in one or two sentences 28795

Step 1: Ideal MOSFETs operate in the saturation region where the drain current (Id) is proportio

Explain why ideal mosfets are referred to as square law...

Transcript

00:01 In this question, we are asked about a mosfet at different current voltage relations of mosfet in saturation and non -saturation bias region.

00:12 So mosfet saturation and non -saturation bias region.

00:22 So the first question is in saturation region, the drain current, how does it affect in the saturation and non -saturation? so the drain current id is primarily given by the equation which is vgs -v.

00:40 It is proportional to, not by the equation, vgs which is the gate source voltage minus v threshold voltage divided by the channel length l.

00:50 It is proportional to that.

00:52 So this is inversely proportional to the l.

00:55 So when the l becomes scaled down by a factor of k, some factor of k, so what it means is that when it's scaled up by factor of k, what happens is that the drain current will be reduced by a factor of k.

01:15 So id will become, id dash will become 1 by kth of id.

01:24 So that's what happens.

01:25 So if it is, let's say 0 .6 times, then it will be id dash will be equal to 0 .6, 60 % of id.

01:34 It will be scaled down.

01:36 Now in non -saturation bias region, the drain current is influenced by non -saturation.

01:42 This is saturation.

01:44 This non -saturation region, the drain current is influenced by the proportional to the same vas, sorry, vgs minus v threshold divided by the channel effective channel length that is l effective.

02:00 So effective channel length is proportional to the square root of gate length.

02:07 So l effective is proportional to the square root of gate length l.

02:12 It is proportional to the square root of gate length.

02:15 So the reducing the gate length by a factor of k will effectively decrease this by a factor of root of k, square root of k.

02:26 So id dash will be equal to 0.

02:32 Sorry, root of k times square root of k times id.

02:43 So that will, that is what is 1 by square root of k by id.

02:47 So that is what is going to happen in the non -saturation region.

02:53 Now going to the second question, the power dissipation per mosfet like b part, power dissipation per mosfet, power is equal to v times i.

03:04 So the drain current, let's call this id, right? so and drain source voltage which is ds.

03:13 So in saturation region, right in saturation bias region, the drain current is inversely scales with the gate length.

03:23 Id is inversely scales with the gate length, gate length.

03:31 So, so the drain source voltage is typically assumed to be a constant...

Question

Explain why ideal MOSFETs are referred to as “square law” devices in one or two sentences.

Question

Explain why ideal MOSFETs are referred to as “square law” devices in one or two sentences.

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