TI E2E Community
Low Power RF & Wireless Connectivity
Low Power RF Bluetooth® Low Energy & ANT Forum
Automatic gain control on CC254x
I stumbled on AGC in the user's guide and would like to know what it is in details. Has anyone modified its value and what were the results of such modifications. Is the AGC same on either cc2540 or cc2541? I can appreciate TI's answer to clarify or point me to the right place where I can read more about this topic.
thanks in advance
It is there to keep the received RF signal at a level which gives good dynamic range for demodulation as the signal level at the RF input can vary over many orders of magnitude based on rss (a fundamental part of most radio receivers). It is presumably controlled by the BLE stack link layer. What would you hope to achieve by modifying it?
There is no AGC on CC2540. On the CC2541, there is an option to use a simple AGC in proprietary mode, but there is no AGC when running BLE. This AGC is recommended only for 2 Mbps.
The reason for not running AGC on these chips is that the front-end is capable of receiving strong signals. It will be clipping, but since the modulation format is FSK (GFSK or MSK), there is no information i the amplitude anyway. On the 2 Mbps mode, the receiver runs zero-IF, and in this case strong signals will give problems for the receiver. This is why an AGC is needed for 2 Mbps.
The AGC running in proprietary mode on CC2541 is described in Section 220.127.116.11. If you are using CC2541 for BLE only, this chapter is not relevant.
we conducted a chamber testing and we observed a gain of about -12dBm when distance is 60cm. I will be sending the report to other TI Engineers and would like to include you since you have provided the above answer.
All content and materials on this site are provided "as is". TI and its respective suppliers and providers of content make no representations about the suitability of these materials for any purpose and disclaim all warranties and conditions with regard to these materials, including but not limited to all implied warranties and conditions of merchantability, fitness for a particular purpose, title and non-infringement of any third party intellectual property right. TI and its respective suppliers and providers of content make no representations about the suitability of these materials for any purpose and disclaim all warranties and conditions with respect to these materials. No license, either express or implied, by estoppel or otherwise, is granted by TI. Use of the information on this site may require a license from a third party, or a license from TI.
TI is a global semiconductor design and manufacturing company. Innovate with 100,000+ analog ICs andembedded processors, along with software, tools and the industry’s largest sales/support staff.