[sdiy] Integrator output bias question

[Donald Tillman]

On Oct 28, 2013, at 12:15 PM, Justin Owen <juzowen at gmail.com> wrote:

> I started with this: http://www.sdiy.org/juz/I_01a.png - pretty much every combo I tried, the output waveform of the active integrator wanted to head south.

Ahhh... some issues:

1. It's never practical to run an integrator open loop.  The slightest input offset voltage will eventually drive the output to a rail.  

2. A high value bleed resistor across the cap should help.  But your input resistor is already way high.  So you'll want to scale that down, and the cap up.

3. In this particular simulation, the input waveform starts at a positive peak, which itself is a positive bias, and that could very well explain the downward direction of the output.

  -- Don
--
Don Tillman
Palo Alto, California
don at till.com
http://www.till.com