I need to modify a 100kHz square wave (~1Vp-p) to make it look like the blue waveform.
Could someone direct me to some reading or help lead me through the theory?
I currently can only find info on inverters, using square waves to get ac.
Added: I'm not sure on what the fall time is suppose to be on the pulse but Id like to know how to change that anyway
So you want the output to promptly fall to a constant non-zero value.
Parallel resistor and capacitor in series with the input and a resistor to ground. The ratio of the two resistors sets the persistent voltage and the capacitor defines the initial fall time constant.
Thanks Paul. I'll give it a go.
Why do you want this?
To add to Paul__B's solution: "resistor voltage divider" and "high pass filter" will lead you to important Google results.
See also "differentiator circuit."
Hi,
Can you clarify the voltage axis please.
If you are using Paint, you can add text.
Thanks .. Tom... 
0.5V and -0.5V for square wave levels.
0.05V and -0.05V for non-zero levels.
Hi,
What is the application?
What is producing the waveform and what needs the modified waveform?
Tom...
I am simulating the circuit in LTspice - got the previous questions sorted so thank you all.
But, how come there is a large voltage spike where the cap charges up and discharges? (1st picture)
I have managed a work around (2nd picture) but I would like to know what's going on.
Is it the software: the fact I have set the voltage source to have a very fast rise and fall time (not like what I would really get from my function generator in real life).
Would I see this spike in a practical setting please?
Tom it is just a challenge/helping a friend out - and I am trying to learn more about electronics, so I can apply this to anything I might need to down the line.
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