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TRF3722: Driving IF with singled ended input

Antenna_Head
Genius 11395 points
Part Number: TRF3722
Other Parts Discussed in Thread: DAC38J84

Team-

Customer would like to drive IF port of TRF3722 single-ended, i.e. one side of the differential input drive, while the other side is terminated.

Certainly this will impact certain performance parameters; that would be expected.

Want to know if this will work with reduced performance and if AC or some sort of DC bias should be placed on the unused/terminated input.

From the data sheet it appears that a common mode of 0.25V should be on BBQ_P/BBQ_N.  Is it OK to bias this with a voltage divider having 0.25V output and output impedance of ~50 Ohms to terminate the BBQ_N port?  We would then drive BBQ_P with single-ended 50 Ohm system.  

Thanks, Best, Steve

  • 0
    TI__Guru 66014 points

    Hi Steve,

    We have done all the characterization of the TRF3722 with either the DAC38J84 high speed DAC with differential output or the Keysight ESG signal generator (also differential). It is very difficult to comment on the overall performance hit when driving with single ended as this part was not designed for such operation. 

    Single ended source will typically have higher even order harmonics than differential source. Besides the typically higher baseband even order harmonic, the LO leakage will also be higher. The even order harmonic and inter modulation will create DC components, and resulting higher LO leakage. 

    TI cannot recommend this operation based on the high level analysis above.

    However, if the customer choose to do so, then they need to make sure each leg is properly biased to 0.25V, either through resistor divider or RF choke of some sort.

    -Kang