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External LNA Gain Control limit

Category: Datasheet/Specs
Product Number: ADRV9002

Hi,

I have questions about External LNA Gain Control with the following hardware setup:

- ADRV9002 on BytePipe x9002 module (Zynq UltraScale+ host)
- ADRF5717 variable attenuator in front of RX1 (channel 1 only)
- Attenuator control: 3-bit parallel, LE tied to VDD, D5 -> AGPIO_8, D6 -> AGPIO_9. Accessible states: 0 / 16 / 32 / 48 dB
- TES version 0.29.0

I have read UG-1828 (p.180) states that "N + M + L should not exceed 29 dB" per LNA.

A previous EZ thread answered confirms that the AGC actually supports up to 87 dB of external attenuation via the same 2 AGPIO pins, and that the user guide is in the process of being updated:

(https://ez.analog.com/rf/wide-band-rf-transceivers/design-support-adrv9001-adrv9007/f/q-a/579723/external-lna-with-agc)

There is also the EZ article "Implement an External LNA in TES":
(https://ez.analog.com/rf/wide-band-rf-transceivers/tes-gui-software-support-adrv9001-adrv9007/w/documents/32216/implement-an-external-lna-in-tes)

The ADRF5717 has physical 16 dB steps:
N = 16, M = 16, L = 16 -> 48 dB total external attenuation

Given the 87 dB limit confirmed in the previous thread, 48 dB should fit comfortably. Still, I have some open questions:

1. Based on the 87 dB total external attenuation feature mentioned in the previous thread, is it possible to configure a single external attenuator (one physical chip, 4 states, 2 AGPIO control bits) with N=M=L=16 dB summing to 48 dB total? Or does the 87 dB feature require multiple external LNA devices in cascade?

2. TES gain table generation issue (TES 0.29.0):
When I enable External LNA in the RX configuration of TES with numberLnaGainSteps = 3 and lnaGainSteps_mdB = [16000, 16000, 16000] and try to export the RX gain table, TES does not produce the table.The internal-only gain table exports normally. No clear error message is shown. Could that be the reason the gain table is not generated?

Thanks in advance,

Leo

  • 1. Based on the 87 dB total external attenuation feature mentioned in the previous thread, is it possible to configure a single external attenuator (one physical chip, 4 states, 2 AGPIO control bits) with N=M=L=16 dB summing to 48 dB total? Or does the 87 dB feature require multiple external LNA devices in cascade?

    I don't think so they would be any issue with using the ADRF5717 Digital Attenuator.


    2. TES gain table generation issue (TES 0.29.0):
    When I enable External LNA in the RX configuration of TES with numberLnaGainSteps = 3 and lnaGainSteps_mdB = [16000, 16000, 16000] and try to export the RX gain table, TES does not produce the table.The internal-only gain table exports normally. No clear error message is shown. Could that be the reason the gain table is not generated?

    Can you please crosscheck from "Customizing the Rx Gain Table" section and see if we are missing anything?