Hello!

So i'm looking for a circuit that can make a square-root of a voltage. I know it's pretty complex, and i'm aware of log solutions, TI note 31 etc ... But none of them are accurate and they all need a very specific specification.

So does anyone know about some good solutions, or has any new ideias?

Thanks!

 

But none of them are accurate and they all need a very specific specification.

What circuits have you found to be inaccurate? How accurate to you want them to be?

 

Look at Figure 15 in this multiplier's data sheet.
That's probably about as accurate as you can get using analog techniques.

 

Hello!

So i'm looking for a circuit that can make a square-root of a voltage. I know it's pretty complex, and i'm aware of log solutions, TI note 31 etc ... But none of them are accurate and they all need a very specific specification.

So does anyone know about some good solutions, or has any new ideias?

Thanks!

What's the application?

 

Hello!

So i'm looking for a circuit that can make a square-root of a voltage. I know it's pretty complex, and i'm aware of log solutions, TI note 31 etc ... But none of them are accurate and they all need a very specific specification.

So does anyone know about some good solutions, or has any new ideias?

Thanks!

There's probably something in the NS application notes floating about somewhere online.

The appnotes are pretty old - so you'll have to research modern replacements for some of the listed semiconductors.

The principles have been around since they thought analogue computers could compete with digital.

 

The principles have been around since they thought analogue computers could compete with digital

Actually analog(ue) computers were around long before digital.
It took some time before digital could compete with the speed of analog..

 

Actually analog(ue) computers were around long before digital.
It took some time before digital could compete with the speed of analog..

Did I say they hadn't?!!!

 

Did I say they hadn't?!!!

Well, your statement I referenced sounded like it to me.

 

Somebody has to say it, so it might as well be me. Have you considered using a microcontroller rather than an analogue circuit?

 

Simple.

Take a voltage generator y.
Feed it into both inputs of a multiplier circuit to give y^2.
Compare the input voltage x with y^2.
Feed the error voltage back into the y generator.
y = √x

 

Simple.

Take a voltage generator y.
Feed it into both inputs of a multiplier circuit to give y^2.
Compare the input voltage x with y^2.
Feed the error voltage back into the y generator.
y = √x

You want to be really careful about the gain required in the vicinity of the origin.