Name: DACメソッド R2Rラダー (DAC Methods R2R Ladder)
Uploaded: 2021-01-14T06:37:59.000Z
Duration: 8 min 58 s
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

This is Jim Pytel from Columbia Gorge Community College.

This lecture is entitled Digital Analog Conversion Methods R2R

In our last discussion about digital to analog conversion,

we made use of binary weighted input circuit

As easy as it was to understand the binary weighted input

They're not exactly the most scalable methods.

For example, if I wanted to expand this to a fifth position,

I have to do some fundamental change of those inputs.

Additionally, think about the manufacturer ability

Are resistors of those values even commercially available?

So if the picture if your using a huge selection of resistors

Compare and contrast to what we were just about to discuss here.

you can optionally take out the resistive ladder and feed it

into an amplifier, which we'll talk about in a little bit here.

But an R2R2 does not necessarily need that amplifier right now.

As confusing as this circuit may look here,

2RR, 2RR. The only difference being this 2R2R at the very end.

It stands to conjecture that if I wanted to perhaps expand

to a fourth bit position, all I would have to do is put

in that 2RR sixth bit position, so on and so forth.

You're expanding those functional blocks using the same

resistive values and that's exactly how it happens.

basically how we did this was the lowest significant bit

The most significant bit contributed more.

Exact same thing for the resistive ladder network here.

How we do that though is kind of different.

Notice my output voltage is right there and for D0

to contribute anything, it's got to go through one stage,

And each time it's successfully being divided.

And notice how I've heard D3 only has go to through one stage

And the reason why I'm saying it's optional

to put an amplifier there at the end is this circuit will perform

and there will be a single analog voltage of we put

However, it's limited to that range of that logic load.

If we wanted to somehow step it up and down or perhaps we want

to amplify or attenuate it, we could use operational amplifier

at the very end and adjust the gain with its feedback resistor.

So let's go ahead and perform a quick analysis

and what you'll find is you can be making use of evidence there.

So I know [Inaudible] you're going to have to use some

of your basic understands of electronics to understand this.

because of its repetitive functional unit nature.

Namely this 2RR combination and what you try

to do is just basically take your basic resistive network

and give it these divisions right there, right there

What does [Inaudible] states is basically I can take the open

with the voltage source removed, and replace it

with the voltage equivalent and a resistor in series.

So what we can do is kind of analyze each stage

Think about it from the perspective of D0

and all I've done between this top diagram here is all I did

From the perspective of D0, it is being voltage divided

between two identical resistances, 2R, 2R.

Say for example, D0 was a logical value of five volts.

Well it should be five volts divided by two and a half volts.

So we've already performed the division of that.

What is the Thevenin equivalent resistance at that point

where we remove that source and what you get is basically 2Rs

in parallel, which is the single R-value here.