Moving Voltage waveform range using amplifier - request info

[dwaindibbley]

We are a software development company, and as the old Joke goes, How
many software engineers does it take...... you know the rest. We require
what we believe to be a simple amplifier circuit, and so are looking for the
equivalent of us Geniei in the Analogue electronics field. We are willing
to pay for this design. (As long as it works!). Say a few hundred US$. We
can build the design and test it.

What we have is a waveform entering our AtoD converter at a high
speed. The AtoD is very fast (500Meg) so is only low resolution, at 8 bit.
Our waveform varies between 2.5 to 3.5V. The problem we have is that at 8
bits, it is not enough to re-structure the waveform as we have to set the
AtoD to +/-5V. That gives us about 25 point range. What we would like to
do, is linearly change the voltage to say 0 - 1V, or even better -1V to 1V
we can then set the AtoD to a shorter voltage range giving us much better
resolution. We are open to any suggestions, such as where we would be able
to go and find such help. I have been told that an Inverting amplifier is
what we need, not sure if this is the case. Obviously the circuit needs to
be accurate, and fast.


Thanks


Wayne

 

[PeteS]

There are some questions here:

1. You say the voltage waveform varies between 2.5 and 3.5V. Does that
means the signal is bounded by 2.5V (lowest value) and 3.5V (highest
value) ? Or alternatively that the peak to peak value ranges between
2.5V and 3.5V (I suspect the former because of the statement on data
points, but it needs to be clarified).

2. What is the actual frequency range of the signal involved? You say
you have a 500M converter. Is that input frequency range, or it's
sample rate? (The sample rate has to be significantly higher than the
stated bandwidth - usually by a factor of at least 5:1 and at a minimum

2:1 - the Nyquist limit).

3. What is the source impedance of the signal? At these sorts of
frequencies, that becomes quite an issue.

4. I assume you are doing SinX/X compensation (a digitised signal
normally gets this spectral response) if you are reconstructing the
signal - fairly straightforward in software provided you have the
processing power.

The design you want may be fairly straightforward, but the above
questions would need to be answered first.

Cheers

PeteS