ADRF6755 Baseband IQ Input signals are attenuating when connected to ADRF

Hi,

We are generating the I,Q differential signals at the required level 540mv DC mean and 280mv P-P on each line.

But when we connect the these 4 lines(I+,I-, Q+, Q-) to ADRF, all these four signals are loading and changing values to 540mv  mean and 180mv P-P

We tried giving them to 450mv P-P also, still they are attenuating.

What could be the reason? How can I resolve this?

Regards

Parents
  • 0
    •  Analog Employees 
    on Oct 6, 2020 8:29 PM

    Hi,

    Baseband inputs of ADRF6755 are high impedance (30Kohm at 1MHz, roll off at higher frequency) and it should be driven from a low impedance source. Then the voltage swing level on the source is driven to baseband inputs on ADRF6755 fully. If the source impedance is not low enough compared to the input impedance, the driven voltage to ADRF6755 will be down by voltage divider. And  we recommend the dc bias level at 500 mV +/- 25mV. 

    Please refer to "Baseband Inputs" section on page 24 in datasheet.

    Thanks

    Tony

Reply
  • 0
    •  Analog Employees 
    on Oct 6, 2020 8:29 PM

    Hi,

    Baseband inputs of ADRF6755 are high impedance (30Kohm at 1MHz, roll off at higher frequency) and it should be driven from a low impedance source. Then the voltage swing level on the source is driven to baseband inputs on ADRF6755 fully. If the source impedance is not low enough compared to the input impedance, the driven voltage to ADRF6755 will be down by voltage divider. And  we recommend the dc bias level at 500 mV +/- 25mV. 

    Please refer to "Baseband Inputs" section on page 24 in datasheet.

    Thanks

    Tony

Children