next up previous contents
Next: High-Pass Filter Up: Passive RC Filters Previous: Low-Pass Filter

Approximate Integrater

The low-pass filter acts as an approximate integrater at high frequencies. Assume

and integrate to obtain

The DC term is unimportant and may be dropped to obtain

We define

For a low-pass filter at high frequencies and

Thus the low-pass filter integrates at high frequencies but also attenuates the signal by 1/(RC).

Doug Gingrich
Tue Jul 13 16:55:15 EDT 1999