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anti-imaging filter

Category: Hardware
Product Number: AD9833

Hi, everyone.

we are using waveform generator AD9833 to generate BB waveform for IQ modulator, as recommended anti-imaging filter need to be placed to reduce distortion from modulator.

According to CN 0304  Circuit Notes 0304 a CF op amp as op amp need to be used since the maximum current output is approximately 4 mA, actually AD8014 have been used, also another reason to use AD8014 for impedance matching as written in Circuit Notes " provides a low impedance drive source for a high quality 50 Ω filter"

* Do we need to use such this configuration in CN 0304 with AD9833?  or another configuration or other type of op amp ?

Regards

thanks for your support

Eng  maged 

  • ADI North America will be on winter shutdown starting December 25, 2023; perhaps another community member can assist you until our return on January 8, 2024.
  • The AD9834 and AD9833 are very close to each other with the AD9834 requiring an external 200-ohm resistor and the AD9833 already having one internal to the IC. But in order to facilitate the filter design (so it can be made as a 50-ohm block) and to provide isolation between the DDS' DAC output and the filter so as to not load down the DAC, the OPAMP is desired. I would say you follow the design on CN-0304 and then design your filter to be placed between the OPAMP's output and the IQ modulator input.