Is it possible to avoid the RF AGC setting switching between different levels during all RX time?

Question

Hi, 
 
 For our DA1469x range application, it is much better if the RF AGC setting is fixed to a custom level. 
 Is it possible to avoid the RF AGC setting switching between different levels during all RX time? 
 
 Best regards, 
 Peter

OV_Renesas · Answer

Hi Peter, We do not think that this would be a good idea. When the RF AGC is set to a fixed setting, the risk is that when the incoming signal is weak, there is too much noise in the I/Q singal. At the other hand, it would 'clip' when the incoming signal is strong. Both will result in worse or bad ranging performance. From DA1469x Datasheet: ' The LNA and IF Filter gains are controlled by the AGC. This provides the necessary signal conditioning prior to digitalization .' Best Regards, OV_Renesas

OV_Renesas · Answer

Hi Peter, Apologies for the delay. Did you try to do the following setting? O ne can prevent AGC switching with RF_AGC_CTRL2_REG [AGCSETTING_SEL] Best Regards, OV_Renesas

OV_Renesas · Answer

Hi Peter, Thank you for the reply. Please find below the reply from the Radio Team as well: 
 With AGCSETTING_SEL at 1, you make sure the AGC is fixed. The gain in the RX path is provided by AGCSETTING_WR. This is a 4 bit number (0 to 15). The actual gain of the receiver is defined by the AGC Look-up-table (LUT): 
 RF_AGC_LUT_0123_REG - > high gain 
 RF_ACG_LUT_4567_REG -> lower gain 
 RF_AGC_LUT_89AB_REG -> even lower gain. 
 RF_AGC_LUT_CDEF_REG -> lowest gain 
 
 So, for example: 
 AGCSETTING_SEL = 1 and AGCSETTING_WR = 0, the receiver gain is fixed at the highest gain minus 6 dB 
 AGCSETTING_SEL =1 and AGCSETTING_WR = 1, the receiver gain is fixed with the highest gain minus 12 dB 
 etc. 
 
 Note: if one wants to know the exact gain value (in dB), one has to create the RF_AGC_LUT_****_REG table: 
 AGC_SETTING, LNA gain, VGA1 gain, VGA2 gain 
 0, 0, 0, 1 (highest gain minus 6 dB due to 1*6 dB lower gain in VGA2) 
 1, 0, 0, 2 (highest gain minus 12 dB due to 2*6 dB lower gain in VGA2 
 2, 1, 0, 2 (highest gain minus 18 dB due to 2*6 dB lower gain in VGA2 and 1*6 dB lower gain in LNA) 
 3, 
 4, 
 5, 
 6, 
 7, 
 8, 
 9,

Hope this information helps. 
 
 Best Regards, OV_Renesas