Chaps,
I've been tinkering with a simple opamp-based 2 pole Salen-Key low pass filter, like this one. Ra and Rb are 10K, Ca is 10n ceramic, Cb is 1n5 MKT (just what I had handy in the parts drawer). I'm using an LM833 as the opamp.
The problem I have is that I'm seeing a rising DC voltage at the output, which starts at 0V at switch-on and rises all the way up to the positive supply rail over the course of a few minutes. I'm assuming what I'm seeing is one or both of the capacitors being gradually charged up (input bias current maybe?). Is there a simple way to prevent this charging from occurring? I did a quick Google and couldn't find anything that described the effect I'm seeing.
Thanks.
I've been tinkering with a simple opamp-based 2 pole Salen-Key low pass filter, like this one. Ra and Rb are 10K, Ca is 10n ceramic, Cb is 1n5 MKT (just what I had handy in the parts drawer). I'm using an LM833 as the opamp.
The problem I have is that I'm seeing a rising DC voltage at the output, which starts at 0V at switch-on and rises all the way up to the positive supply rail over the course of a few minutes. I'm assuming what I'm seeing is one or both of the capacitors being gradually charged up (input bias current maybe?). Is there a simple way to prevent this charging from occurring? I did a quick Google and couldn't find anything that described the effect I'm seeing.
Thanks.