TINA/Spice/ADC3223: input impedance setup on simulation

Patrick Chen(TPE System & Application)

Part Number: ADC3223
Other Parts Discussed in Thread: TINA-TI,

Tool/software: TINA-TI or Spice Models

Hi Sir,

My customer is considering to use ADC3223 on their system and would like to run simulation first, but they do not know how to set the impedance, could you help to advise?

They are trying to simulate a differential type filter into ADC input, and frequency range is 0~100MHz.

Currently they only could simulate single end input, therefore they will short INAM to GND and single end signal to INAP.

On page64 of ADC3223 datasheet, it shows that the impedance is 6.3K ohm || 3.7pF @ DC, is this for differential impedance?

How to set it for single end?

Or any suggestion for simulation?

Thanks,

Patrick

over 5 years ago

0 dBrock over 5 years ago

TI__Genius 12780 points

Hi Patrick,

This is for differential impedance.

To convert this to single ended impedance, you can half the resistance and double the capacitance. For instance, at 100 MHz, the differential impedance is 3k ohms and about 3.7 pF. The single ended impedance would be 1.5k ohms and 7.4 pF.

ADC3223 Analog Input Impedance.TSC

Best Regards,

Dan

0 Patrick Chen(TPE System & Application) over 5 years ago in reply to dBrock

TI__Expert 3430 points

Hi Sir,
Thanks for your help.
Do you have S-parameter for ADC3223 to share?

Thanks,
Patrick

0 dBrock over 5 years ago in reply to Patrick Chen(TPE System & Application)

TI__Genius 12780 points

Hi Patrick,

This information is not explicitly stated in the data sheet. You can transform the resistance and capacitance given in the plots (shared from the data sheet in my last post) to find the impedance. This can then be transformed into S-parameter information. There are a lot of free tools available on the internet that can help with this.

Best Regards,

Dan

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TINA/Spice/ADC3223: input impedance setup on simulation