Need programmable cutoff LP filter

May 05, 2006 2 Replies
A

Hi all,



Does anyone have a recommendation for a digitally programmed low-pass filter like Maxim's 270/271 except with a lower range for the cutoff frequency?



I need an adjustable cutoff from about 200 - 2000 Hz (the 270's range is



1 - 25 kHz). I would prefer not to use a programmable filter that uses resistors or pots because I need high precision. I'll have at least 5 of these, and the cutoff frequencies have to match to +- 2 Hz or so (audio application).

My other option I guess is to get filters for which you adjust the cutoff with an external clock, have one clock serve all, and adjust the clock frequency.



But I'd sure like to know about any easily programmable low-pass filter chips.



Thanks in advance, Amanda


Vote
Twitter Facebook LinkedIn
R

2Hz accuracy ... The concept of filter slope and dB is known ? What order should these filters have ?

Rene

Ing.Buero R.Tschaggelar - http://www.ibrtses.com & commercial newsgroups - http://www.talkto.net
Vote
Twitter Facebook LinkedIn
K

2Hz/2000Hz = 0.1%

You really need to go digital with this if you don't want a lot of trimming to be needed.

Since you are making a low pass, going digital can work quite nicely. ADCs and DACs that do 24 bits for the audio band are getting common. You don't really needs one that good however. You can follow the DAC with a fixed low pass filter at, lets say, 5KHz.

-- kensmith@rahul.net forging knowledge
Vote
Twitter Facebook LinkedIn

Join the Discussion

Have something to add? Share your thoughts — no account required.

Didn't find your answer?

Ask the community — no account required