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ADRV9002 used for measuring scattering parameters

Category: Hardware
Product Number: ADRV9002


I am planning to use ADRV9002 for setting up an instrumentation that can measure scattering parameters. S11 and S21. For this I need three receivers (V1+, V1-, V2-) to be able to calculate S11 and S21. 

question: 1) From the datasheet I understand there are Rx1 and Rx2. However, what is the difference in Rx1A and Rx1B? is it multiplexed and simultaneously be used to to demodulate/receive the same carrier frequency? since I only have two receivers, would I need another transceiver chip?

question: 2) the power level of the Tx, does it have to be calibrated with a loopback? and after calibration would it be stable? 

question: 3) could the V1+ be obtained with the internal loop back? I understand it uses one of the receivers?

question: 4) on page 112 of UG-1828, "Transmitter NCO internal Signal Source"--> can this feature be used as the source/input signal for this type of measurement? Some more elaboration on how will be very helpful.

  • 1. You can use either RX1A or RX1B, only one at a time. It is multiplexed and you can switch it through API. You would need more than one chip if your application require more than two channels running simultaneously. .

    2. Power level is stable, but only the typical value is specified in the data sheet. Internal loopback is used only for internal calibration algorithm, and not available to user. 

    3. It'd be appreciated if you could clarify your question. The specified transmit power is the power delivered to 50 ohm load, which can be measured with an instrument.

    4. You can use internal NCO a signal source in the transmit path. You may an option to use NCO instead of tone generated by FPGA. You can enable it using the TES GUI tool: [main menu] ->  [Configure] -> [Radio] -> [ Transmit Data Source] -> [Use internal tone generation]

    I suppose you need some kind of bridge to isolate forward and reflected power if you want to realize a network analyzer along with ADRV9002.

    Hope this answer your question. 

  • Yes a directional coupler to isolate the forward and reflected power. 
    elaboration on 3: yes all ports will be 50 Ohm. by V1+ I mean the transmitted signal from say Tx1. Could it be said to be known with the internal calibration settings. Say V1- (the reflected signal on port1) and V2- (the incident signal on port 2) will use Rx1 and Rx2 respectively? Is there a way to avoid using another transceiver? if not can you recommend another receiver chip that can be synchronized with the ADRV9002.

  • Thanks. TX1 power level is known and specified in the data sheet, but only typical value is published in the data sheet. You may want to implement your own calibration mechanism if the accuracy matters.

    I don't see a problem in using RX1 and RX2 to measure V1- and V2-, respectively. You can also switch the port RX1A and RX1B on the fly so that you can measure V1+ through Rx1B once in a while for the purpose of calibration and use Rx1A to measure V1- and RX2A to measure V2-. Does this makes sense to you?

  • that is what I am planning to do. Still dont have the hardware in. Just wanted to make sure I understood the docs correctly.

  • Hi, I have to correct an error in my previous answer. There is a switch in hardware to choose between Rx1A and Rx1B, and you can decide which one to use before starting initialization/calibration, but firmware does not allow you to switch the port on the fly after calibration is completed. So you need to have an external analog switch to select V1+ and V1-, or you can reset the chip and go through initialization/ calibration again, which may take few seconds, and then start over to use a different rx port. This may be acceptable to your case if you don't have to calibrate TX power very often. Sorry for the bad news.

  • I am thinking if I have V1- on Rx1A and then V2- on Rx2A. For V1+, is it possible to use ILB1? which connects with Rx1B(??) internally?

    or, if this is the case should I use another Transceiver chip and use the synchronization pins to sync them?

    Could I use two evaluation boards and synchronize them that way?

  • It is not possible to use Rx1B in that way. ILB is used only for internal calibration algorithm and not available to user. You can use MCS feature to synchronize the second chip so that both of the chips have the same deterministic latency. Whether to use synchronization depends on your system requirement. Without MCS, the latency of two chips will not be same, but the difference stays same once the chip is initialized and calibrated. Yes, you can use two evaluation board and synchronize them