Transformation of Sin wave

Question

I was impressed by your solution of my previous problem. So, I think you may help me with this image

I have made huge circuit with OpAmps and couple of active and passive components, but I suppose that it can be solved much easier. Thank you!

Upd: I was said that the solution is wrong and this problem needs much theoretical than practical approach. So, I divided input voltage on 2 signals, now I need to process and concatenate them. The questions are following: 1. Is there another way than integration to process first signal; 2. Actually I don't understand how to dump second signal without capacitor;

Answer 1

YOu can Integrate and Dump with a counter and reset where the frequency of the clock has been converted to the voltage of the input w.r.t. ref.

In an "optimal data discriminator" used in receivers, integrating the data over the entire bit period and then sample it and dump to restart it is the theoretical optimal solution to detect binary noisy data to give the best BER for a low SNR condition.

Just a SWAG on my part IF you wanted to think about using an I&D cct for converting noisy analog data to binary. Or it could be used in data collection instrumentation such as to measure the volume from a flow meter on analog sensor level, where the integral is desired, such as measuring velocity from acceleration over a period of time with a known initial condition. Another SWAG. Most people start with simple 4016 cmos switches to dump the caps but then can get feedthru spikes.

Answer 2

This might be what you are looking for (assuming you are still trying to solve this problem). This is stevenvh's answer drawn out as a schematic, and simplified by removing the AND gate.

Rather than use two sin wave sources, here I am using a capacitor and resistor to create a little less than 90º phase shift. I'm not sure exactly how accurate you need this. Alternatively, you can just use the 90º phase shift voltage source you showed in your schematic.

These two signals are turned into phase shifted square waves by the comparators. If you use comparators with open-drain outputs, then you don't need the AND gate, as the outputs are basically half an AND gate each. You just need to add a pull-up resistor, and you're done.

Notes:

• You will need comparators with an open-drain output.
• There is no explicit hysteresis in this design. Either use a comparator with internal hysteresis, or add some.
• If you really the output to be perfect, then you need exactly 90º phase shift, so you'll have to use the opamp differentiator that stevenvh mentioned in the previous question.