What are the Benefits of a Single RF Pin on Transceivers

[njfl]

Lately, I hae been encountering a lot of devices (Bluetooth, UWB) that use a single RF pin for I/O. For example, on a Bluetooth chip that I am working with, the 48 QFN package only has 1 RF pin and it serves as both TX and RX (since the device can't do both simultaneously).

What is the motivation/advantage of this pin architecture?

 

[Mazz]

The advantage is that there will be no need of an external RF switch from antenna, so it saves space on the board and money.
Mazz

 

[khouly]

this is only valid for TDD systems , so the TX and RX are working in different times

Khouly

 

[njfl]

this is only valid for TDD systems , so the TX and RX are working in different times

Khouly

Yes, that makes sense.

Do you foresee a lot more of the single-IO pin architecture moving forward?

I've seen it in Bluetooth and UltraWideBand devices. Where are some other areas that it is used?

 

[PaulHolland]

Hi, I only see disadvantage unfortunately .. Analog Devices solved it very nicely by using an internal switch and still offering a TX and RX pin making it possible to amplify the signal with a PA or LNA chain. You will see that all real RF companies (Freescale, Analog etc..) are using a TX and RX pin and NOT a combined I/O pin.

 

[njfl]

Hi, I only see disadvantage unfortunately ..

I was under the impression that it is a significant advantage as we go to SOC and SIP packages with multiple features, like CDMA/GSM/UWB/Media/Bluetooth, all in a common package. By having the single IO pins, this reduces the RF pin count. Of course, this wouldn't work for the CDMA and GSM, but for a lot of the other features it could work.

 

[PaulHolland]

Freescale is offering RF chips with and without a common RF pin but still not so many advantages only easy to use for RF-newbies.

 

[njfl]

Freescale is offering RF chips with and without a common RF pin but still not so many advantages only easy to use for RF-newbies.

Are any data sheets available showing parts with both pinouts? I'd be interested to see how tey market that optional offering.

 

[PaulHolland]

https://www.freescale.com/webapp/sps/site/taxonomy.jsp?nodeId=01J4Fs25658166

have a look: TRANSMITT/RECEIVE SWITCH : External/Internal

Analog Devices is offering them only with internal switch BUT still two I/O, TX and RX !. This is much smarter than Freescale )..

 

[njfl]

Thanks for the links.