[SI-LIST] Re: RF board Vs High speed board

Hi Lynne/John
 
RF signals are not necessarily narrowband.
For example, Ultra Wideband Signals (becoming more common these days) have a 
bandwidth of at least 0.25 of the carrier frequency. 
 
The other case that wideband RF is often seen on boards these days is in Direct 
Digital Downconversion architectures. You might see in excess of 1GHz going 
into ADCs, and that's only the IF! In this case the wideband IF often contains 
several signals.
 
Usually some steps have been taken by the implementer of an RF system to limit 
the bandwidth, similar to pre-emphasis and de-emphasis in a high speed digital 
system. So usually the RF board will have slightly more rounded signals, but 
these may have higher rms power than the high speed digital system, especially 
in a PA subsystem.
 
Regards
 
Andrew
 
 
________________________________

From: si-list-bounce@xxxxxxxxxxxxx on behalf of Lynne D. Green
Sent: Wed 24/08/2005 17:27
To: johnnfaq@xxxxxxxxx; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: RF board Vs High speed board



Hello, John,

RF signals are "narrow band", i.e. modulation is superimposed on a carrier
frequency.  The modulation bandwidth is significantly smaller than the
carrier frequency (your car radio is a good example - carrier is around
100kHz, bandwidth is around 20kHz.)  RF requires filtering to remove the
carrier and recover the signal.

High-speed signals are "wide band", i.e. they have significant frequency
content from DC to hundreds of times the modulation rate.  For an ideal
interconnect, filtering is not required to recover the original signal.
(And, although rates are usually given in MHz, they really mean Mbaud.) 

Best regards,
Lynne


"IBIS training when you need it, where you need it."

Dr. Lynne Green
Green Streak Programs
http://www.greenstreakprograms.com
425-788-0412
lgreen22@xxxxxxxxxxxxxx

-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of johnn william
Sent: Wednesday, August 24, 2005 4:19 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] RF board Vs High speed board

Hi All,

Please anyone in group clarify the difference in handling the RF board
compared to normal High speed boards.

Thanks in advance.

John


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