Electronics - RF Transceiver                                                  Home : www.sharetechnote.com

 

 

 

Simply put, RF Transciever IC is an package which has the functionality of RF/Analog Transmition path and reciever path.

Overall illustration of a transmission and reciever path of a communication device is as shown below. Of course, the circuit on real device would be more complicated than this.. and if the mobile device is a mobile phone supporting multiple technology (e.g, CDMA, GSM, WCDMA, LTE), you would have this kind of blocks for each technology. So if you implement all of these technology using discrete component, it would be a huge job and the size of the mobile phone would be like a small laptop PC. In addition, recently with high end mobile devices (e.g, smart phone), these transciever IC start to have many of intelligent technique to reduce energy consumption (e.g, Evelope Tracking, Average Tracking) and to improve ACLR (e.g, Predistortion).

 

 

 

The idea on Tranceiver IC is to put all (or most) of these functionality into a single (or only a few) ICs. Very high level view of Transciever IC would be as shown below. On one side, there goes RF input/output and on the other side  Analog or Digital I/Q signal comes in and out.

 

 

Now we would come across a practical questions. What kind of functional blocks (components) should be packed into the IC. The ideal one (what everyone wish to have) would be as the one marked in green line (labeled as (A)). This has everything in it and you only need to hook up an antenna to the chip and you will get baseband digital I/Qs. But at least as of now, this is too good to be true. The second choice would be the one surrounded by the blue line (B). However, even this is very hard to achieve. For some components, it is very difficult to implemement on IC. For example, the final stage power amplifier would be difficult to packed into an IC because it would tend to generate a lot of heat. Oscillators like VCXO,TCXO is also difficult to sit in the IC and some of the filter (e.g, SAW, BAW filter) is also hard to be replaced by silicon technology. As result, a practical transciever IC would be the one surrounded by black line (C) which contains most of function within the IC but some of functions is still implemented as discrete component. Of course, there are a lot of other possibilities of packaging these components into ICs. You may see some other solutions splitting these into multiple ICs as well.

 

 

One of the most common/high end RF Transciever being used in mobile device would be Qualcomm RTR, WTR series.