ADC12DL3200: How to interface a biased signal to ADC12DL3200 using DC couple

Yao-Hua

Part Number: ADC12DL3200

Hi, there :

The signal we are interested is a signal with bias voltage (0.9V), but the input common-mode voltage of ADC12DL3200 is 0V.

The signal BW ranges from DC to several hundred MHz, so we can only use DC couple interface. How can we convert a

0.9V bias voltage to 0V Vicm when using DC couple? Can you show the suitable level shift circuit for ADC12DL3200?

Thanks.

Yao-Hua

0 RJ Hopper over 4 years ago

Yao-Hua:

There are a few options.

If the signal does not truly go down to DC, but to just a very low frequency, then you can AC couple with a very large capacitor.
If you have access to a negative voltage, then a resistive translation network is possible to achieve 0V at the ADC input
You can add an op-amp buffer that will actively translate to 0V output common mode
If ~20 dB of loss is acceptable, a simple voltage divider to get down to 0.1V would suffice

--RJH

0 Yao-Hua over 4 years ago in reply to RJ Hopper

Hi, Hopper :

Does the resistive translation network look like the following picture?

0 RJ Hopper over 4 years ago in reply to Yao-Hua

Yes. That will do it. --RJH

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