| Author |
Message |
ericgjj
Joined: 24 Aug 2005
Posts: 1
|
 12 Nov 2005 8:36 how to design Very Low Frequency IC Filters |
|
|
|
Hi,
I want to design a low pass filter which -3dB frenquency is 10~100Hz . using a RC and opamp to implenment, the area is very large, beacuse the resistor value about 150MΩ. can anyone help me to reduce the area?
thanks.
|
|
| Back to top |
|
 |
vistapoint
Joined: 20 Feb 2005
Posts: 70
Helped: 1
|
| 12 Nov 2005 9:35 Re: how to design Very Low Frequency IC Filters |
|
|
|
| I have the same question. Co-ask.
|
|
| Back to top |
|
|
JNekas
Joined: 11 Mar 2002
Posts: 332
Helped: 3
|
| 12 Nov 2005 10:26 how to design Very Low Frequency IC Filters |
|
|
|
| Use capacitor multiplier circuits based on OA
|
|
| Back to top |
|
|
Mazz
Joined: 03 Nov 2001
Posts: 493
Helped: 57
|
| 12 Nov 2005 19:26 how to design Very Low Frequency IC Filters |
|
|
|
Switched capacitor technique can be the key.
Now is widely used in integrated filters for FM receivers, bandwidth in the range of tens of KHz.
I hope it can help.
Mazz
|
|
| Back to top |
|
|
KamW
Joined: 16 Jul 2001
Posts: 68
|
| 12 Nov 2005 22:20 Re: how to design Very Low Frequency IC Filters |
|
|
|
There are a few ideas to solve problem. First of all is to use switched capacitor filter - check maxim website. It could be even easier than work with discrete filters.
But if you decide to make discrete filter you should consider use of resistance and capacitance multiplier. It will let you to avoid huge resistor/ capacitor.
But there are problems with stability of such circuits.
In my oppinion the best way to solve problem is to use fpaa from anadigm (www.anadigm.com) With their CABs you could simply prepare any filter. I had asked them for about 0.5Hz filter, and i had one.
Best regards
KamW
|
|
| Back to top |
|
|
suria3
Joined: 05 Mar 2004
Posts: 314
Helped: 11
|
| 13 Nov 2005 5:34 Re: how to design Very Low Frequency IC Filters |
|
|
|
Hi,
How about off -chip RC implementation?
Regards,
Suria
|
|
| Back to top |
|
|
