Non-inverting op-amp circuit Khan Academy English Korean

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- [Voiceover] Okay, now we're going to work on our

연산 증폭기 회로에 대해

first Op-amp circuit.

배워보겠습니다

Here's what the circuit's going to look like.

회로가 어떻게 생겼는지 보여드리겠습니다

Watch where it puts the plus sign is on the top on this one.

더하기 표시를 여기에 해보겠습니다

And we're going to have a voltage source over here.

전압원은 여기에 표시해 보겠습니다

This will be plus or minus V in,

입력 신호는

that's our input signal.

더하기나 빼기 그리고 V_in 입니다

And over on the output,

여기 이렇게 연결된

we'll have V out,

and it's hooked up this way.

전력의 양을 나타냅니다

another resistor,

그리고 지면에 연결된

또 다른 저항기는

and this goes back to the inverting input.

반전 입력으로 돌아갑니다

Now we're going to look at this circuit

회로가 어떻게 실행되는지

and see what it does.

자세히 보겠습니다

Now we know that connected up here

the power supply's hooked up

to these points here,

연결되어 있고

and the ground symbol is zero volts.

접지의 기호는 0 V 입니다

And we want to analyze this circuit.

회로를 자세히 보겠습니다

And what do we know about this?

무엇을 알 수 있을까요?

We know that V out equals some gain,

V_o 는 게인을 나타냅니다

I'll write the gain right there.

여기에 적어보겟습니다

A big, big number times V minus,

A x ( V+ - V- )입니다

sorry V plus minus V minus,

A x ( V+ - V- )입니다

and let's label that.

이름을 적어볼게요

V plus is this point right here,

V+ 는 여기에

and V minus is this point right here.

V- 는 여기에 적어줄게요

And we also know that the currents,

전기의 기류를

let's call them i plus and i minus,

equals zero, and that's the currents going in here.

라고 나타낼 수 있습니다

This is i minus here, and that's i plus,

i- 그리고 i+ 입니다

and we know those are both zero.

둘의 값은 0 입니다

So now what I want to do it describe

회로를 그려서

what's going on inside this triangle symbol in more detail

세모 그림안에

by building a circuit model.

무엇이 벌어지고 있는지 설명해 보겠습니다

Alright, and a circuit model for an amplifier

증폭기 회로입니다

looks like this.

증폭기 회로입니다

We have V minus here, V plus here,

여기에 V- V+ 가 있습니다

so this is V in,

and over on this side we have an,

here's a new symbol that you haven't seen before.

보통 다이아몬드의 모양을 가지고 있는

It's usually drawn as a diamond shape,

새로운 기호를 나타내겠습니다

and this is a voltage source,

전압원의 한 종류 이지만

but it's a special kind of voltage source.

조금 특별하게 불립니다

It's called a voltage-dependent

전압 의존 전압원입니다

voltage source.

전압 의존 전압원입니다

And it's the same as a regular ideal voltage source

보통의 전압원과 비슷하지만

except for one thing,

한가지 다른점이 있습니다

it says that the V, in this case V out,

V 즉 여기서 V_o 는

equals gain times V plus minus V minus.

V_o = A x ( V+ - V- ) 입니다

So the voltage here depends on the voltage somewhere else,

여기에 있는 전압이 다른 전압의 영향을 받는다는 뜻 입니다

and that's what makes it a voltage-dependent,

바로 전압 의존 전압원의

that's what that means.

중요한 특징입니다

So, we've just taken our gain expression here,

식과 회로 모델을 통하여

added, drawn circuit diagram that represents

전압이 회로에서

our voltage expression for our circuit.

어떻게 표현되는지 알아보았습니다

Now, specifically over here

여기에는 값이 0 인

we've drawn an open circuit on V plus,

V+ 개회로와

and V minus so we know that those currents are zero.

V- 를 그려보았습니다

So this model, this circuit sketch

이 회로 모델은

represents our two properties of our Op-amp.

연산 증폭기가 가지고 있는 두 성질을 보여줍니다

So I'm going to take a second here

두번째 식을 가지고

and I'm going to draw the rest of our circuit

surrounding this model,

나머지 회로를 그려보겠습니다

but I need a little bit more space.

공간이 조금 더 필요할 것 같습니다

So let's put in the rest of our circuit here.

회로를 여기에 그려보겠습니다

We had our voltage source,

V+ 와 연결된

connected to V plus,

and that's V in,

and over here we had V out.

여기에는 V_o 가 있습니다

Let's check, V out was connected to two resistors,

V_o 는 두개의 저항기와 연결되어 있습니다

and the bottom is connected to ground,

밑은 지면과

and this was connected there.

연결되어 있습니다

So what our goal is right now,

we want to find V out as a function of V in.

V_in 에 대한 함수 V_o 를 찾아보려고 합니다

That's what we're shooting for.

원하는 바 입니다

So let's see if we can do that.

할 수 있는지 보겠습니다

Let's give our resistors some names.

저항기에 이름을 붙여보겠습니다

Let's call this R1, and R2,

r 1 그리고 r 2 라고 해보겠습니다

our favorite names always,

항상 이렇게 지어주죠

and now everything is labeled.

다 이름을 붙여준 것 같습니다

Now and we can label this point here,

이 지점을 V-

and this point we can call V minus,

V- 라고 부르겠습니다

V- 라고 부르겠습니다

So that's our two unknowns.

미지수 입니다

Our unknowns are V not, V out,

미지수 V_o 그리고 V- 를

and V minus, so let's see if we can find them.

구해보겠습니다

So what I'm going to do is just start

우선 식을 이용하면서

writing some expressions for things that I know are true.

구해보겠습니다

For example, I know that V out

V_o = A x ( V+ - V- ) 입니다

equals A times V plus minus V minus.

V_o = A x ( V+ - V- ) 입니다

Alright, that's what this Op-amp is telling us is true.

연산 증폭기에 의해 식을 구할 수 있었습니다

Now what else do I know?

또 저항기에 대한

Let's look at this resistor chain here.

사실을 알 수 있습니다

This resistor chain actually looks

a lot like a voltage divider,

분압기와 많이 비슷하게 생겼습니다

and it's actually a very good voltage divider.

물론 좋은 분압기 역할을 합니다

Remember we said this current here,

전류는 0 입니다

what is this current here?

전류는 0 입니다

기억하시죠?

I can use the voltage divider expression that I know.

분압기 식을 사용할 수 있습니다

In that case, I know that V minus,

분압기 식은

this is the voltage divider equation,

아래에 있는

저항기 입니다

Times the bottom resistor

저항기 입니다

기억하시나요?

R2 over R1 plus R2,

r 2 / r 1 + r 2 입니다

so the voltage divider expression says that

저항기가 위에 하나

when you have a stack of resistors like this,

저항기가 위에 하나

with the voltage on the top and ground on the bottom,

그리고 밑에 하나 있을 때

this is the expression for the voltage at the midpoint.

중간의 전압을 구할 수 있는 식입니다

Kay, so what I'm going to do next

식을 여기에

is I'm going to take this expression

식을 여기에

and stuff it right in there.

적용해보겠습니다

해보겠습니다

See if we got enough room,

충분한 공간이 있으면 말입니다

okay now let's go over here.

여기에 해보겠습니다

Now I can say that V out

V_o = A x ( V+ - V_o ) x r 2 / r 1 + r 2

equals A times V plus minus V out

times R2 over R1 plus R2,

표현할 수 있습니다

alright so far so good.

잘 해내고 있습니다

Let's keep going, let's keep working on this.

조금만 더 해보겠습니다

V not equals A times V plus minus A V not,

V_o = A x ( V_+ - A x V_o ) x r 2 / r 1 + r 2 입니다

R2 over R1 plus R2.

V_o = A x ( V_+ - A x V_o ) x r 2 / r 1 + r 2 입니다

Alright, so now I'm going to gather all the V not

왼쪽에 있는

terms over on the left hand side.

V_o 에 관한 식을 모아보겠습니다

Let's try that.

So that gives me,

식을 모아봤더니

V not plus A V not,

V_o + A x V_o x r 2 / r 1 + r 2 는

times R2 over R1 plus R2 and that equals

A x V+ 와 같습니다

A times V plus,

A x V+ 와 같습니다

and actually I can change that now

V plus is what?

V plus is V in.

V_in 으로 나타낼 수 있습니다

Okay let's keep going I can factor out the V not.

V_o 의 인수분해 여부를 알아보겠습니다

V_o = 1 + A x r 2 / r 1 + r 2

plus A R2 over R1 plus R2

and that equals AV in.

A V_in 입니다

Alright so we're getting close,

거의 다 왔습니다

and our original goal,

거의 다 왔습니다

we want to find V out in terms of V in.

V_in 에 관한 V_o 의 식을 찾아보려 합니다

So I'm going to take this whole expression here

괄호 안의 식을

and divide it over to the other side,

오른쪽에 있는 식에 나눠보겠습니다

so then I have just V not on this side,

이쪽에는 V_o

and V in on the other side.

그리고 옆에는 V_in 이 있습니다

Make some more room.

공간을 좀 만들어야 할 것 같습니다

I can do that, I can say

물론 V_o = A V_in 를

V not equals A V in

1 + A x r 2 / r 1 + r 2

divided by this big old expression,

이렇게 표현할 수 있습니다

one plus A R2 over R1 plus R2.

이렇게 표현할 수 있습니다

Alright so that's our answer.

정답이 될 수 있습니다

That's the answer.

정답입니다

That's V out equals some function of V in.

V_o 가 V_in 의 함숫값을 나타냅니다

Now I want to make a really important observation here.

중요한 사실을 말씀드리자면

This is going to be a real cool simplification.

더 쉽게 표현할 수 있습니다

Okay, so this is the point where Op-amp

연산 증폭기 이론이

theory gets really cool.

가장 재밌어 지는 부분입니다

Watch what happens here.

무슨일이 일어나는지 잘 보세요

We know that A is a giant number.

A 는 큰 숫자입니다

A is something like 10 to the fifth,

A 는 10^5 아니면

or 10 to the sixth,

10^6 을 나타냅니다

and it's whatever we have here,

값이 무엇이든

if our resistors are sort of normal-sized resistors

보통 크기의 저항기라도

we know that a giant number times a normal number

큰 값을 보통 값에 곱했을 때

is still going to be a very big number compared to one.

1 보다 큰 값을 줄 것입니다

So this one is almost insignificant in this expression

즉 여기에서

down here, so what I'm going to do,

무의미하다는 뜻 입니다

조금만 참고 들어보세요

I'm going to cross it out.

필요없는 부분을

I'm going to say no, I don't need that anymore.

지우고 설명해드리겠습니다

So if this, if this number here, if A is a million,

A 가 100만 즉

10 to the sixth,

10^6 을 나타낸다면

and this expression here is something like one half

1 / 2 와 같다면

then this total thing is one half 10 to the sixth

합산한 값은 1 보다 큰

or a half a million,

1/2 x 10^6 즉 100만의 반이

and that's huge compared to one.

될 것입니다

So I can pretty safely ignore the one,

it's very, very small.

작은 값이기 때문에 무시하셔도 됩니다

Now when I do that,

well look what happens next,

다음에 무슨일이 일어나는지 보겠습니다

now I have A top and bottom in the expression,

식의 위 아래에 A 가 있지만

and I can cancel that too.

이마저도 없앨 수 있습니다

So the A goes away,

now this is pretty astonishing.

A가 사라집니다

We have this amplifier circuit

증폭 회로에서

and all of a sudden I have an expression here

A 가 없는 식

where A doesn't appear,

즉 이득이 없다면

the gain does not appear,

무엇이 될까요

and what does this turn into?

무엇이 될까요

This is called V not

V_o = V_in x r 1 + r 2 / r 2

equals V in, times what?

Times R1 plus R2,

표현할 수 있습니다

표현할 수 있습니다

So our amplifier, our feedback circuit came down to

증폭기 회로에서

V out is V in multiplied by the ratio of the resistors

V_o 는 V_in 곱하기 회로에 더해진

that we added to the circuit.

저항기의 비율과 같습니다

This is one of the really cool properties of using Op-amps

회로에서 연산 증폭기를 쓰면 좋은 점은

in circuits, really high-gain amplifiers.

이득을 많이 생산해내는 증폭기이기 때문입니다

What we've done is

we have chosen the gain of our circuit

구성에 따라

based on the components that we picked

증폭기에 더할

to add to the amplifier.

회로의 이득을 정한 것입니다

It's not determined by the gain of the amplifier

물론 증폭기의 이득이 아주 크지 않으면

as long as the amplifier gain is really, really big.

증폭기에 이득에 따라 결정되지 않습니다

And for Op-amps, that's a good assumption,

물른 연산 증폭기에 관한 좋은 접근이긴 합니다

it is really big.

아주 큽니다

So this expression came out with a positive sign, right?

양성의 부호를 가지고 있는 식입니다

All the R's are positive values,

모든 r 이 양성입니다

so this is referred to as a non-inverting

비반전 증폭기입니다

Op-amp circuit amplifier.

비반전 증폭기입니다

So just to do a quick example,

if R1 and R2 are the same,

r 1 과 r 2 가 똑같다고 가정해 보겠습니다

then we end up with an expression that looks like this

V out equals R1 plus R2, R plus R over R is equal to two

V_o = r 1 + r 2 그리고 r + r / r = 2

so the gain is two times V in.

즉 얻는 값이 2 x V_in 입니다

So just to do a quick sketch

설명하기 쉽게 그려보겠습니다

just to remind ourselves what this looks like,

V_in 이 이렇게 있었고

V_in 이 이렇게 있었고

and we had what out here?

We had a resistor,

저항기가 있었습니다

we had a resistor to the ground,

지면에 저항기가 있었습니다

and this is V out.

So this is the configuration of a non-inverting amplifier

연산 증폭기를 이용한

built with an Op-amp,

비반전 증폭기 배열을 나타냅니다

the two resistors in this voltage divider string

분압기에 위치해 있는 저항기의 줄은

connected to the negative input.

네거티브 입력과 연결되어 있습니다

So that's what non-inverting Op-amp circuit looks like,

비반전 증폭기가 이렇게 생겼습니다

and it's going to be one of the familiar

도식을 배우고

patterns that you see over and over again

회로를 디자인하면서

as you read schematics and you design your own circuits.

이와 비슷한 패턴을 많이 발견할 것입니다

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