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Connecting TRF371135 (IQ demodulator) and LMH5401 (Active Balun)

Ramede Justo
Prodigy 10 points
Other Parts Discussed in Thread: LMH5401, TRF371135

Hi,

I'm using the LMH5401 (as an active balun 2-3GHz) as an input device for the TRF371135 (IQ demodulator). Both need to be powered using a 5V single-supply. That gives me a common-mode voltage of 2.5V at the outputs OUT+ and OUT- of the LMH5401.

Will I have any problems connecting these outputs directly (without any DC blocking capacitor) to the MIX_IN_P and MIX_IN_N inputs of the TRF371135?

The schematic below might make it clear.

Thanks,

Ramede.

  • 0
    TI__Guru 71529 points
    Hi Ramede,
    I checked the datasheet and the EVM schematic of TRF371135, and I believe we have always been using the TRF371135 with the mixer input ac coupled (with the transformer/balun circuit). I have also measured the input common mode voltage (internal biasing) of TRF371135 on an EVM, and it was measured about 2.8V, which does not match the 2.5V of the LMH amp. Since your operating range is between 2 to 3GHz, you may want to consider having some sort of AC coupling network in between the amp and TRF input.

    -Kang