Dual Band WLAN Diplexer?

[aaron_do]

Hi all,


in a dual-band WLAN, a diplexer is normally used after to combine the 2GHz and 5GHz bands after their FEMs. I'm just wondering why do we use a diplexer and not an SPDT? The two bands don't seem to operate concurrently...



thanks,
Aaron

 

[D.A.(Tony)Stewart]

a properly designed Diplex filter can have adequate Return Loss (>15dB) and transmission band loss (<0.2dB) and be cheaper and lower loss than a good SPDT RF switch with Pin diodes.

 

[aaron_do]

I see. I didn't realize a diplexer would be cheaper. Not sure about the lower loss though. Both are on the order of 0.5 dB. Also, its a waste because most FEMs already have a SPDT to cover TX/RX, so an SP4T would cover dual-band TX/RX with not much increase in the loss...


Aaron

 

[aaron_do]

Are you sure there's no functional reason for having a diplexer instead of a switch? I'm looking at the SE5516A from Skyworks, which is a dual-band FEM, and they still use a diplexer between the two PAs...

 

[volker@muehlhaus]

in a dual-band WLAN, a diplexer is normally used after to combine the 2GHz and 5GHz bands after their FEMs. I'm just wondering why do we use a diplexer and not an SPDT? The two bands don't seem to operate concurrently...

In any case, with a diplexer the receiver than search for base stations on both bands simultaneously (without switching).

 

[aaron_do]

In any case, with a diplexer the receiver than search for base stations on both bands simultaneously (without switching).

Makes sense. Thanks for the help.

Aaron