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All right. Let's get started. I guess this watch is a couple minutes fast. First a quick announcement. In case you have forgotten, your lab notebooks are due tomorrow with the post-lab exercises for the first lab.

OK, so I am going to continue with amplifiers today. And to just give you a sense of where we headed, we have this five lecture sequence covering different aspects of amplifiers with dependent sources and showed how we could build an amplifier with it on Tuesday.

Today I am going to show you a real device that implements a dependent source. And then next Tuesday we will talk about analysis of an amplifier. Wednesday is our quiz. Thursday and the Tuesday after that we then talk about small signal analysis and small signal use of the amplifier.

Today we will talk about the MOSFET amplifier. So let's start with a quick review. And in the last lecture, I showed you that I could build a amplifier using a dependent source. And a dependent source worked as follows.

Let's say I had a circuit and I connected a dependent source into the circuit. Let's say in this example I have a current source. So this is some circuit. And the current i is a function of some parameter in the circuit.

That's why this is a dependent source. This is a dependent current source. So it could be that I have some element inside. And I measure, I sample the voltage across the element or between any two points in the circuit.

And, in this little example here, this current could be dependent on that voltage. So notice that although I showed you the two terminals of the dependent source that carried a current, there is another implicit port, another implicit terminal there.

And that terminal there is called the "control port" of the dependent source at which I apply a voltage or current that will control the value of the current source. As a quick aside. There is a small glitch with the tools in your tool chest.

We talked about the superposition technique where you were taught to turn on one source at a time, for a linear circuit one source at a time, and then sum up the responses to all the sources acting one at a time.

Well, what do you do about dependent sources? A dependent source is a source. And we have to modify the superposition statement just a little bit. And for details you can look at Section 3.5.1 of your course notes on the details and some examples on how to do this.

So the approach is very simple, actually. The approach is, for the purpose of superposition, to not treat your dependent source as sources that you turn on and turn off. So what you do is when you do superposition with dependent sources simply leave all your dependent sources in the circuit.

Just leave them in there and turn on and off only your independent sources. So look at the response of the circuit by turning on your independent sources one at a time and summing up the responses.

And your dependent sources stay within the circuit and simply analyze them as you do anything else. So essentially what it says is that just be a little cautious when you have dependent sources, but the basic method applies almost without any change.

The readings for today's lecture are Section 7.3 to 7.6. So since we are going to build up on the dependent source amplifier, let me start with a quick review of that amplifier. We built our amplifier as follows.

We connected our dependent source in the following manner.

OK, so I am going to continue with amplifiers today. And to just give you a sense of where we headed, we have this five lecture sequence covering different aspects of amplifiers with dependent sources and showed how we could build an amplifier with it on Tuesday.

Today I am going to show you a real device that implements a dependent source. And then next Tuesday we will talk about analysis of an amplifier. Wednesday is our quiz. Thursday and the Tuesday after that we then talk about small signal analysis and small signal use of the amplifier.

Today we will talk about the MOSFET amplifier. So let's start with a quick review. And in the last lecture, I showed you that I could build a amplifier using a dependent source. And a dependent source worked as follows.

Let's say I had a circuit and I connected a dependent source into the circuit. Let's say in this example I have a current source. So this is some circuit. And the current i is a function of some parameter in the circuit.

That's why this is a dependent source. This is a dependent current source. So it could be that I have some element inside. And I measure, I sample the voltage across the element or between any two points in the circuit.

And, in this little example here, this current could be dependent on that voltage. So notice that although I showed you the two terminals of the dependent source that carried a current, there is another implicit port, another implicit terminal there.

And that terminal there is called the "control port" of the dependent source at which I apply a voltage or current that will control the value of the current source. As a quick aside. There is a small glitch with the tools in your tool chest.

We talked about the superposition technique where you were taught to turn on one source at a time, for a linear circuit one source at a time, and then sum up the responses to all the sources acting one at a time.

Well, what do you do about dependent sources? A dependent source is a source. And we have to modify the superposition statement just a little bit. And for details you can look at Section 3.5.1 of your course notes on the details and some examples on how to do this.

So the approach is very simple, actually. The approach is, for the purpose of superposition, to not treat your dependent source as sources that you turn on and turn off. So what you do is when you do superposition with dependent sources simply leave all your dependent sources in the circuit.

Just leave them in there and turn on and off only your independent sources. So look at the response of the circuit by turning on your independent sources one at a time and summing up the responses.

And your dependent sources stay within the circuit and simply analyze them as you do anything else. So essentially what it says is that just be a little cautious when you have dependent sources, but the basic method applies almost without any change.

The readings for today's lecture are Section 7.3 to 7.6. So since we are going to build up on the dependent source amplifier, let me start with a quick review of that amplifier. We built our amplifier as follows.

We connected our dependent source in the following manner.

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