configuration with external LNA in AD9364

manideep on Sep 6, 2021

I designed customized RF tranceiver board with AD9364. I have a customize RF board with an external LNA and output connected to the RF transceiver board., I worked in fast AGC mode with out external LNA , its working fine . when i tried to give GPIO_O output to my external LNA to control attenuation of external LNA .The AGC loop is working fine in power on condition , when i tried to change the input of system, the AGC is going to failed .

I changed the default gain table as per UG -570 and enabled the bit of D6 in the register of 0x026. please can any one suggest me how to fix my problem ?

Vinod

on Sep 6, 2021 11:03 AM
0
How is GPO configured in ad9361_gpo_setup function ?

Are you using manual GPO control or update of gain automatically by updating the gain table?

From user Guide.

Setting Bit D4 of Register 0x026 puts the GPOs in manual control mode. Use the upper nibble (four bits) of Register 0x027 as the GPO logic level controls. GPO_3 uses D7; GPO_2 uses D6, GPO_1 uses D5, GPO_0 uses D4. In this mode, the lower nibble of Register 0x26 is ignored.
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manideep on Sep 7, 2021 12:01 AM in reply to Vinod
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thank you reply.

I configured GPO-0 ,by updating the gain table . i am not using manual control. the read data of 0x026 is 0xA0.
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srimoyi

on Sep 7, 2021 11:08 AM in reply to manideep
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Are you able to change the gain of the external LNA using GPO0 as per the gain table? Can you share with us your modified gain table? At what input level, the AGC is failing? Is the AGC failing only at those power levels in which AGC is using the added external LNA gain ?
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manideep on Sep 8, 2021 12:47 AM in reply to srimoyi

Yes, i am able to change the gain of the external LNA through GPO0. I am changing the attenuation of the external LNA through GPO0. My external LNA gain values are 28 dB if attenuation is off or 14 dB if attenuation is on . The AGC loop is working fine in the mode of attenuation off for all input levels.

To made simulation easy, I have prepared two gain tables of external LNA control on and off . I have simulated the conditions one by one by placing respective gain tables in the program. The AGC loop is working fine with the gain table of external LNA OFF for all input levels.

The observations with the gain table of external LNA ON are :

1. AGC is working fine only on initialization .

2. Going to calibration out even for 1 dB change in input level. Again if I reinitialize, AGC is working good for changed input levels.

Here with i am enclosing two gain tables.

Fullscreen gain_tables.txt Download

               
    // Gain table with External LNA off control

                { 0x00, 0x00, 0x20 }, { 0x00, 0x00, 0x00 }, { 0x00, 0x00, 0x00 },//2
		{ 0x00, 0x00, 0x00 }, { 0x00, 0x00, 0x00 }, { 0x00, 0x01, 0x00 },//5
		{ 0x00, 0x02, 0x00 }, { 0x00, 0x03, 0x00 }, { 0x01, 0x01, 0x20 },
		{ 0x01, 0x02, 0x00 }, { 0x01, 0x03, 0x00 }, { 0x01, 0x04, 0x20 },
		{ 0x01, 0x05, 0x00 }, { 0x01, 0x06, 0x00 }, { 0x01, 0x07, 0x00 },
		{ 0x01, 0x08, 0x00 }, { 0x01, 0x09, 0x00 }, { 0x01, 0x0A, 0x00 },
		{ 0x01, 0x0B, 0x00 }, { 0x01, 0x0C, 0x00 }, { 0x02, 0x08, 0x20 },
		{ 0x02, 0x09, 0x00 }, { 0x02, 0x0A, 0x00 }, { 0x02, 0x0B, 0x20 },
		{ 0x02, 0x0C, 0x00 }, { 0x02, 0x0D, 0x00 }, { 0x02, 0x0E, 0x00 },//26
		{ 0x02, 0x0F, 0x00 }, { 0x02, 0x2A, 0x20 }, { 0x02, 0x2B, 0x00 },
		{ 0x04, 0x27, 0x20 }, { 0x04, 0x28, 0x00 }, { 0x04, 0x29, 0x00 },//32
		{ 0x04, 0x2A, 0x00 }, { 0x04, 0x2B, 0x00 }, { 0x04, 0x2C, 0x00 },//35
		{ 0x04, 0x2D, 0x00 }, { 0x24, 0x20, 0x20 }, { 0x24, 0x21, 0x00 },//0x24 is replaced with  0x44  for 37,38,39
		{ 0x44, 0x22, 0x00 }, { 0x44, 0x23, 0x00 }, { 0x44, 0x24, 0x00 },
		{ 0x44, 0x25, 0x00 }, { 0x44, 0x26, 0x00 }, { 0x44, 0x27, 0x00 },
		{ 0x44, 0x28, 0x00 }, { 0x44, 0x29, 0x00 }, { 0x44, 0x2A, 0x00 },
		{ 0x44, 0x2B, 0x00 }, { 0x44, 0x2C, 0x00 }, { 0x44, 0x2D, 0x00 },
		{ 0x44, 0x2E, 0x00 }, { 0x64, 0x2E, 0x20 }, { 0x64, 0x2F, 0x00 },
		{ 0x64, 0x30, 0x00 }, { 0x64, 0x31, 0x00 }, { 0x64, 0x32, 0x00 },
		{ 0x64, 0x33, 0x00 }, { 0x64, 0x34, 0x00 }, { 0x64, 0x35, 0x00 },
		{ 0x64, 0x36, 0x00 }, { 0x64, 0x37, 0x00 }, { 0x64, 0x38, 0x00 },
		{ 0x65, 0x38, 0x20 }, { 0x66, 0x38, 0x20 }, { 0x67, 0x38, 0x20 },
		{ 0x68, 0x38, 0x20 }, { 0x69, 0x38, 0x20 }, { 0x6A, 0x38, 0x20 },
		{ 0x6B, 0x38, 0x20 }, { 0x6C, 0x38, 0x20 }, { 0x6D, 0x38, 0x20 },
            	{ 0x6E, 0x38, 0x20 }, { 0x6F, 0x38, 0x20 }


  // Gain table with External LNA on control

                { 0x80, 0x00, 0x20 }, { 0x80, 0x00, 0x00 }, { 0x80, 0x00, 0x00 },//2
		{ 0x80, 0x00, 0x00 }, { 0x80, 0x00, 0x00 }, { 0x80, 0x01, 0x00 },//5
		{ 0x80, 0x02, 0x00 }, { 0x80, 0x03, 0x00 }, { 0x81, 0x01, 0x20 },
		{ 0x81, 0x02, 0x00 }, { 0x81, 0x03, 0x00 }, { 0x81, 0x04, 0x20 },
		{ 0x81, 0x05, 0x00 }, { 0x81, 0x06, 0x00 }, { 0x81, 0x07, 0x00 },
	        { 0x81, 0x08, 0x00 }, { 0x81, 0x09, 0x00 }, { 0x81, 0x0A, 0x00 },
		{ 0x81, 0x0B, 0x00 }, { 0x81, 0x0C, 0x00 }, { 0x82, 0x08, 0x20 },
		{ 0x82, 0x09, 0x00 }, { 0x82, 0x0A, 0x00 }, { 0x82, 0x0B, 0x20 },
		{ 0x82, 0x0C, 0x00 }, { 0x82, 0x0D, 0x00 }, { 0x82, 0x0E, 0x00 },//26
		{ 0x82, 0x0F, 0x00 }, { 0x82, 0x2A, 0x20 }, { 0x82, 0x2B, 0x00 },
		{ 0x84, 0x27, 0x20 }, { 0x84, 0x28, 0x00 }, { 0x84, 0x29, 0x00 },//32
		{ 0x84, 0x2A, 0x00 }, { 0x84, 0x2B, 0x00 }, { 0x84, 0x2C, 0x00 },//35
		{ 0x84, 0x2D, 0x00 }, { 0xA4, 0x20, 0x20 }, { 0xA4, 0x21, 0x00 },//0x24 is replaced with  0x44  for 37,38,39
		{ 0xC4, 0x22, 0x00 }, { 0xC4, 0x23, 0x00 }, { 0xC4, 0x24, 0x00 },
		{ 0xC4, 0x25, 0x00 }, { 0xC4, 0x26, 0x00 }, { 0xC4, 0x27, 0x00 },
		{ 0xC4, 0x28, 0x00 }, { 0xC4, 0x29, 0x00 }, { 0xC4, 0x2A, 0x00 },
                { 0xC4, 0x2B, 0x00 }, { 0xC4, 0x2C, 0x00 }, { 0xC4, 0x2D, 0x00 },
		{ 0xC4, 0x2E, 0x00 }, { 0xE4, 0x2E, 0x20 }, { 0xE4, 0x2F, 0x00 },
		{ 0xE4, 0x30, 0x00 }, { 0xE4, 0x31, 0x00 }, { 0xE4, 0x32, 0x00 },
		{ 0xE4, 0x33, 0x00 }, { 0xE4, 0x34, 0x00 }, { 0xE4, 0x35, 0x00 },
		{ 0xE4, 0x36, 0x00 }, { 0xE4, 0x37, 0x00 }, { 0xE4, 0x38, 0x00 },
		{ 0xE5, 0x38, 0x20 }, { 0xE6, 0x38, 0x20 }, { 0xE7, 0x38, 0x20 },
		{ 0xE8, 0x38, 0x20 }, { 0xE9, 0x38, 0x20 }, { 0xEA, 0x38, 0x20 },
		{ 0xEB, 0x38, 0x20 }, { 0xEC, 0x38, 0x20 }, { 0xED, 0x38, 0x20 },
		{ 0xEE, 0x38, 0x20 }, { 0xEF, 0x38, 0x20 }

srimoyi

on Sep 14, 2021 6:46 AM in reply to manideep
0
manideep said:
Going to calibration out even for 1 dB change in input level. Again if I reinitialize, AGC is working good for changed input levels.

What do you mean by calibration out? Are you checking the convergence bit to determine the cal failure? Is the DC offset cal failing?

The DC cal bit in the gain table that runs the cal should only be set to 1 when the internal LMT(LNA, MIXER,TIA) gain index changes(DC cal bit should follow the default gain table). It should not be set to 1 with the external LNA index change.

Make sure that there is no signal input given to the RX port while running callibrations.
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configuration with external LNA in AD9364