Digital down-conversion and cross-talk

Started by krishk24 4 months ago2 replieslatest reply 4 months ago90 views

Hello folks

I am looking at the AD9082 for a high bandwidth application. There are 2 Numerically Controlled Osc (NCO) for each ADC core. datasheet is pasted here -

Here is the question-

after digitization by the ADC core, there are 3 operations as I understand from the block diagram -

1) FIR filtering before decimation

2) Decimation

3) digital down-conversion (multiplication by cos and -sin carriers) to place the complex signal at baseband for demod and detection by DSP

So given that I have 2 NCOs, I am planning on use each NCO to perform the channelization by programming them independently based on where the channels are located in IF.

Now what happens is both complex channels are located around DC. The plan is to route the 2 complex channels separately by JESD204C lanes to the Modem.

Should I be worried about any cross talk between the 2 channels since they are located around DC and share common HW inside the AD9082 chip ? Or am I just being paranoid ?

Let me know. Thanks.

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Reply by emebMay 19, 2020

By what mechanism do you anticipate crosstalk?

All signal processing after the ADC is done in the digital domain. Unless there's something seriously wrong with the datapath, there should be no crosstalk between the different channels.

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Reply by weetabixharryMay 20, 2020

The thing I feel more worried about is whether a real-valued mixer is definitely suitable for your application.

However, as per emeb's reply, I don't feel worried about crosstalk.