TRF371125: Baseband impedance

Ololade S.

Prodigy 10 points

Part Number: TRF371125
Other Parts Discussed in Thread: TRF3722, TRF3705

Hello,

How much load is the TRF371125 able to drive at the baseband outputs?

I would like to interface the TRF371125 outputs with 100Ω (differential) but I see the datasheet characterizes at 1kΩ.

I would like to inquire the same about the TRF3722 (at the baseband inputs).

Thank you.

over 4 years ago

0 Kang Hsia over 4 years ago

TI__Guru* 81535 points

Hi,

You are correct that the datasheet specifies the TRF371125 is meant to drive high impedance ADC input. We will need to check internally to see the capability of 100ohm differential load

The TRF3722 and TRF3705 have the same baseband interface. You may see below app note on guides to interface these two modulator inputs:

https://www.ti.com/lit/ug/slua647a/slua647a.pdf?ts=1636599803202&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FDAC3484

Thank you

-Kang

+1 RJ Hopper over 4 years ago in reply to Kang Hsia

TI__Mastermind 18095 points

As mentioned, the TRF3711 is designed to interface with a high impedance of an ADC. The device does not perform well when loaded with a low impedance like 100 ohm differential. With this load, you will see current draw increase and linearity significantly degrade.

If a 100 ohm load is deemed necessary, then you could introduce an impedance transformer (similar to one used on the TRF3711 EVM). This will pass AC signals but not DC. Another alternative is to include an additional buffer stage capable of driving a 100 ohm load.

--RJH

0 Ololade S. over 4 years ago in reply to Kang Hsia

Prodigy 10 points

Thank you Kang.

0 Ololade S. over 4 years ago in reply to RJ Hopper

Prodigy 10 points

Thank you RJH

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TRF371125: Baseband impedance