ADC3242: Analog Input circuit, tracking window, CLKP/CLKN polarity, Figure 135.

Jason Petras

Part Number: ADC3242
Other Parts Discussed in Thread: THS4541

Hi TI support,

May I please have your help with a few basic questions about the ADC3242?

1. Can you please provide an equivalent analog input circuit?

2. Can you please confirm that the acquisition point (sample switch open) is determined by the negative edge of CLKP/CLKM (plus Ta, of course)? I was expecting it on the positive edge.

3. Can you please confirm that the tracking window opens on the positive edge of CLKP/CLKM?

4. Lastly, in Figure 135, is it safe to assume that CLKINP = pin CLKP, CLKINM = pin CLKM and Ta = ta? Not looking to be nit-picky.... just making sure there isn't something subtle that I'm missing.

Thank you,

Jason

over 6 years ago

0 Clay Uhing over 6 years ago

TI__Prodigy 280 points

Hi Jason,
We've received your question and I have forwarded it to an engineer familiar with the ADC3242.
Best Regards,
Clay

0 Jason Petras over 6 years ago in reply to Clay Uhing

Intellectual 650 points

Thank you Clay. I appreciate the redirect.

0 jim s over 6 years ago in reply to Jason Petras

TI__Guru* 91947 points

ADC3242.docxJason,

Please see attachment for answers to your questions.

Regards,

Jim

0 Jason Petras over 6 years ago in reply to jim s

Intellectual 650 points

Hi Jim,

Thank you for the feedback. We are still a little puzzled since the waveform below produces the largest difference between two adjacent samples - we can adjust our sample phase vs incoming signal. The only thing I would ask is your opinion on the small bump on the input signal (yellow) at falling edge of the clock (blue). Looks like the opening of the sample window. Would you say otherwise? We are using TI's THS4541 diff amp and have 50ohm 40MHz filter before the ADC. I know this isn't "enough" information. But, I'm just looking for your opinion.

Beyond this opinion, thank you for the help. I will mark this as solved when I hear back.

0 jim s over 6 years ago in reply to Jason Petras

TI__Guru* 91947 points

Jason,

The glitch is sent back to the driving circuitry on both edges (opening and closing of sampling switch) but typically a larger glitch is seen when the sampling switch opens, which is the falling edge.

Regards,

Jim

0 Jason Petras over 6 years ago in reply to jim s

Intellectual 650 points

Thank you Jim. I do appreciate the double check.

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ADC3242: Analog Input circuit, tracking window, CLKP/CLKN polarity, Figure 135.