DAC7568: How to integrate an active LPF to improve the output aliasing?

Poh Kok Keng

Part Number: DAC7568

Dear Sir/madam,

We have a DAC system and wish to integrate an active lowpass filter to improve the output aliasing, the device datasheet shows:

Using ±6V and external 5V ref, we modified to ext 2.5V ref and ±3.3V power supply, is this ok? Any proposal for the filter components?

below are the one i draft out, any comment?

Best regards,

kpk

0 Akhilesh K over 6 years ago

Hi,

What's the output voltage you are looking for ? is it +/-2.5V ?

Also cut off frequency of the filter ? Do you have any settling time requirements at the output?

Regards,

0 Poh Kok Keng over 6 years ago in reply to Akhilesh K

Genius 5512 points

hi AK,

Yes, required output Voltage is +-2.5V
Around fs=40kHz to 200 kHz. Which frequency make sense? We want to use one channel at maximum speed or all channels at minimum speed
Speed should be 1/fs , no other constraints

Best Rgds,

kpk

0 Akhilesh K over 6 years ago in reply to Poh Kok Keng

Hi,

Please find the component value for the filter.

R1 ---> 649 Ohms

R2 ---> 11.8K

C1 ---> 360pF

C2 ---> 3.6nF

All these are designed with -3dB frequency at 50KHz.

Regards,

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