The Designer's Guide Community Forum

The Designer's Guide Community Forum
https://designers-guide.org/forum/YaBB.pl
Design >> RF Design >> Filter Specification in CDMA IS95
https://designers-guide.org/forum/YaBB.pl?num=1103988931

Message started by chingkailun on Dec 25^th, 2004, 7:35am

Title: Filter Specification in CDMA IS95
Post by chingkailun on Dec 25^th, 2004, 7:35am

Hi all,

I am doing bandpass filter for wireless receiver front end(IF conversion architecture). The filter is IF filter which is situated right after the mixer.

Is there any standard specification for the filter(CDMA IS95 standard)?
I know the standard bandwidth of the filter in CDMA is 1.25MHz.
If anyone knows the standard such as
1. centre frequency,
2. gain,
3. input equivalent noise/noise figure,
4. linearity(IP3/compression point),
5. attenuation, and others relevant info, plz let me know.

Thanks!I really need your help...

Kailun

Title: Re: Filter Specification in CDMA IS95
Post by DaveB on Jan 11^th, 2005, 8:16pm

I'm not sure that I'm reading your request correctly, but here it goes. Bandpass filters for RF are generally passive, crystal or SAW based devices.

1) The center frequency is your IF Frequency
2) Gain (Loss Actually) is as small as possible.
3) Noise figure is the inverse of the gain
4) Linearity generally isn't a concern for filters.
5) Those are really the big ones. You might want to think about spurious rejection and ultimate attenuation floors as well, but that is left as an exercise for the student :)

Title: Re: Filter Specification in CDMA IS95
Post by boa on Jan 11^th, 2005, 9:09pm

I think that the answers to you questions are not in the CDMA standart, but depend on the frequency planning of your receiver.

Title: Re: Filter Specification in CDMA IS95
Post by DaveB on Jan 15^th, 2005, 11:47am

Boa:

you are right, most of these fall into fairly generic Front end design.

Dave