AFE58JD18: AFE's with DC coupled LNA input?

Jean-Luc Bolli

Part Number: AFE58JD18
Other Parts Discussed in Thread: ADS52J90

Tool/software:

Hello,

I am looking for a 8 or 16 channels AFE's, having ADC's clocking simultaneously at 25 MS/s or higher, minimum 14 bits resolution. A critical request for my application is to have a DC coupled input, either single ended or differential. It seems the LNA of this part cannot be configured as DC coupled. Is it true, or some tricks could be applied? If not, do you have other parts to advice?

Best regards, Jean-Luc Bolli

8 months ago

0 Sachin H K 8 months ago

TI__Expert 7725 points

Hi,

All our AFE supports single ended AC coupled input only . What is your application ?

0 Jean-Luc Bolli 8 months ago in reply to Sachin H K

Prodigy 205 points

Hi Sachin,

My application is a multi-channels data acquisition FMC board, and I need a bandwidth from DC to 30 MHz. The ADC's specifications are given above. Some of your AFE's would be perfect, except that the amplifiers are not DC-coupled, at least for the connection to the input pin. Do you know if inside the chip, the amplifiers are DC-coupled? It would be very nice to know, because one can imagine that with proper biasing the signal source to the input pin, it could be possible to get DC-coupling.

0 Sachin H K 8 months ago in reply to Jean-Luc Bolli

TI__Expert 7725 points

Can you evaluate ADS52J90 adc? This is multichannel ADC which has dc coupling option .

0 Jean-Luc Bolli 8 months ago in reply to Sachin H K

Prodigy 205 points

Yes, for sure. This ADC is very interesting for the application and will probably be selected. Now I need to design a compact front-end (32 channels on a FMC) without using an AFE, due to the lack of DC coupling capabilities.

0 Jean-Luc Bolli 8 months ago in reply to Jean-Luc Bolli

Prodigy 205 points

Hello Sachin,

I have read the ADS52J90 data sheet, but I didn't find an electrical model for the ADC inputs. Can you provide one? Even a simple one will be OK, differential resistance, differential and common mode capacitances.

Best regards, Jean-Luc

0 Sachin H K 8 months ago in reply to Jean-Luc Bolli

TI__Expert 7725 points

Can you please refer to Figure 91. Analog Input Sampling Network in datasheet ?

0 Jean-Luc Bolli 8 months ago in reply to Sachin H K

Prodigy 205 points

Hi Sachin,

Oh, very sorry, I miss this figure! Thank for the reply.

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AFE58JD18: AFE's with DC coupled LNA input?