RF signal fanout solution -- component selection

haopeng han

Other Parts Discussed in Thread: LMH6559

Hi,

We are currently looking for a solution to fanout a 50~1000MHz, 0dBm sine-wave RF signal to 32 single-ended channels. It willl be part of a phase measurement circuit. The reference sine-wave comes from a PLL and is differential (can be single ended).

We are considering using op amps as voltage followers to build this fanout buffer array. Could you please suggest a chip or a solution? It would be great if there can be reference circuits.

Thanks in advance!

Best,

over 6 years ago

0 Jacob Freet over 6 years ago

TI__Expert 7875 points

Hi,

A few questions about your circuit.

What is the total load to the circuit that will be presented to the amplifier?
Is the phase matching of the channels critical to the application?

Regards,

0 haopeng han over 6 years ago in reply to Jacob Freet

Expert 1120 points

Hi Jacob,

Thanks for your reply.

The amplifier of each channel will interface a phase&magnitude detector AD8302 (as INPA). Attached the input circuit and parameters. A hierarchical design is OK.

Yes, the phase matching of the channels is critical since the buffered signal is used as a reference.

Thanks,

0 Jacob Freet over 6 years ago in reply to haopeng han

TI__Expert 7875 points

Hi HP,

From the input schematic it looks like you'll be looking at about 4k Ohm load from each phase detector for all 32 channels in parallel, you might be able to drive that load with something like the LMH6559. That part is a close loop buffer so it does not require any external components, and using a single device will eliminate the issue of phase matching between multiple devices.

Regards,

0 haopeng han over 6 years ago in reply to Jacob Freet

Expert 1120 points

Thanks Jacob, I will look into it.

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RF signal fanout solution -- component selection