A ckt to clamp a signal of 1.67to-1.67v to 3.3to0v. Signal is about 50kS/s. I needed to implement this practically so that i can give input to adc of a microcontroller. So the signal accuracy is crucial.

 

Hi raisal,
Welcome to AAC.
Please post your circuit attempt, so that we can help.

E

 

i found something like this. But don't know about the values needed to be given

 

Hi,
Have you not covered this topic in your college studies?

E

 

A ckt to clamp a signal of 1.67to-1.67v to 3.3to0v. Signal is about 50kS/s. I needed to implement this practically so that i can give input to adc of a microcontroller. So the signal accuracy is crucial.

Quick question...

Are you talking about a level converter circuit? That sounds more like what you are after but I'll wait for your reply.
A clamp circuit usually acts as a limiter that limits the signal to some max or min value.

 

View attachment 329367i found something like this. But don't know about the values needed to be given

That circuit is AC coupled, so you will lose any information about the DC level.

 

So the signal accuracy is crucial.

What accuracy?
How many bits is the A/D converter?
Is the reference voltage for the A/D available?

 

This circuit takes the signal and centers it at 1/2 of the supply voltage. This is good for ADC looking at a AC signal.

 

What accuracy?
How many bits is the A/D converter?
Is the reference voltage for the A/D available?

16-bit adc. Im thinking vdda 3.3 vssa gnd

 

Quick question...

Are you talking about a level converter circuit? That sounds more like what you are after but I'll wait for your reply.
A clamp circuit usually acts as a limiter that limits the signal to some max or min value.

Yes, a level shifter

 

Yes, a level shifter

But do you need a DC level shifter, or are you just interested in the AC component of the signal?

 

16-bit adc. Im thinking vdda 3.3 vssa gnd

Yes, a level shifter

Getting 16-bit accuracy (0.0015%) in a level shifter is not trivial.
What accuracy does your signal really require?
Is it just 16-bit resolution, with some lower accuracy (say 1% or perhaps better).

 

Hi raisal,
As this appears to be a College assignment, we want to see your best attempt at answering, before we start helping.

Moderation.

 

This circuit takes the signal and centers it at 1/2 of the supply voltage. This is good for ADC looking at a AC signal.
View attachment 329397

Hi,

That looks like it could work except for the DC offset and drift. R4 and R5 might have to be lowered in value, as low as 2k each but I doubt any lower than that. The value of the capacitor would have to be large enough to keep the attenuation down also at the lowest frequency.

 

Getting 16-bit accuracy (0.0015%) in a level shifter is not trivial.
What accuracy does your signal really require?
Is it just 16-bit resolution, with some lower accuracy (say 1% or perhaps better).

I am guessing that the accuracy does not have to be too high because 1.67+1.67 does not equal 3.3

 

But do you need a DC level shifter, or are you just interested in the AC component of the signal?

Did you mean that it might be rectified instead of having the DC offset shifted?

 

I don't know enough about what is being measured.
I don't understand the word clamping?

A ckt to clamp a signal of 1.67to-1.67v to 3.3to0v.

What frequency?
Do you need to measure DC? If so, there will be no capacitors. Just add (3.3v/2) to the signal. Problem is that 1.65V may not be 1/2 of the supply voltage.
If AC only then see post #8.
Is the wave form sign wave like the power line? Or is it complex?

 

Did you mean that it might be rectified instead of having the DC offset shifted?

Just wondering what the TS wants to know about the signal. It's a 50kHz signal of some kind, but suppose it was PWM - if so the average DC level would vary with the PWM ratio on the side that is capacitively coupled.

 

the signal. It's a 50kHz signal of some kind

I think the ADC will sample at 50khz.

 

I think the ADC will sample at 50khz.

Nyquist says that it will have to sample at more than 100kHz