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ADF7030-1 Differential LNA input matching

Hi All,

We are developing the product using ADF7030-1.

I have a few questions of Receive differential LNA matching.

First of all, we made a circuit that is not combined type matching network of Tx, Rx, though.

On page5 of the datasheet, the input impedance of 169MHz in Rx mode is listed on 78-j20.

However, we designed a circuit where Tx and Rx are not combined, so we can't apply the input impedance of the datasheet.

Q1. Should I design with an unconditional Tx, Rx combined circuit?

Q2. Otherwise, where should the 169MHz Rx mode input impedance value be on the Smith chart?

Q3. And is it necessary to measure the input impedance by short-circuiting the LNA1 and LNA2 pins and attaching port2?

Thank you for your help.

Best regards


Parents Reply
  • Hi WY.P,

    The impedances on page 5 of the datasheet is valid for both separate and combined match. The LNA in RX Mode impedances is for both separate and combined match, while the LNA in Tx Mode is for combined match. Likewise, Optimum PA Load While in Transmit is for both combined and separate match, while PA Input Impedance While in Rx is for combined match.

    The design for both combined and separate matching networks for PA and LNA is already available in the Hardware Reference Manual. I'm afraid you'd have to design and test your own matching network if you'd like to use otherwise.


  • Thank you. Aldrich!
    A lot of help and concerns have been resolved!

    There is another point to be asked about.

    When measuring impedance with a network analyzer, Port1 is of course the ANT input, and does Port2 need to short-circuit the LNA1 pin and LNA2 pin to measure the impedance?

    If you measure the LNA1 pin and LNA2 pin separately, you will still get other impedance values, so I don't know how to do. Because I handled for the first time ever with a Transceiver for me.

    Great Thanks,