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matching nrf24 to 100ohms balanced

iot_newb

I want to use the nrf24l01+ with the se2436 apmlifier, but the input of the amplifier requires an input of 100ohms balanced, while the nrf24 has a balanced output of 15ohm+j88ohm according to the datasheet.

Can I build a matching circuit to directly connect these to devices or is it recommended to first transform the signal to 50ohms unbalanced and then back again to 100ohms balanced.

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    In-band, mathematically there is no difference between transforming straight to 100ohms balanced or going through 50ohms unbalanced first. Going through 50ohm unbalanced first is just a complicated effort that will surely give you more insertion loss, lower yields and will consume more board space. Also, unless you use a broadband balun you will lose the second order harmonic suppression that is natural to baluns.

    So, no you should go straight to 100ohm balanced. The spec says "antenna load impedance" of 15+j88. Normally this is inferred to mean recommended antenna load. So the input impedance of the nRF is the conjugate or 15-j88. Though I would recommend you clarify this aspect of the spec.

    Depending on how you like to do your matches you are either taking 100+j0 and turning it into 15+j88. Or, you are taking 15-j88 and turning it into 100+j0.

    Also, make it a point in your match design to decouple DC from the nRF. I didn't see it in the spec but I think the nRF chips with balanced output present DC on the pins.

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    In-band, mathematically there is no difference between transforming straight to 100ohms balanced or going through 50ohms unbalanced first. Going through 50ohm unbalanced first is just a complicated effort that will surely give you more insertion loss, lower yields and will consume more board space. Also, unless you use a broadband balun you will lose the second order harmonic suppression that is natural to baluns.

    So, no you should go straight to 100ohm balanced. The spec says "antenna load impedance" of 15+j88. Normally this is inferred to mean recommended antenna load. So the input impedance of the nRF is the conjugate or 15-j88. Though I would recommend you clarify this aspect of the spec.

    Depending on how you like to do your matches you are either taking 100+j0 and turning it into 15+j88. Or, you are taking 15-j88 and turning it into 100+j0.

    Also, make it a point in your match design to decouple DC from the nRF. I didn't see it in the spec but I think the nRF chips with balanced output present DC on the pins.

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