Thoughts on this DAC reconstructions filter circuit?

Thread Starter


Joined Apr 16, 2022
I've altered a reconstruction filter circuit to use the LTC728XT instead of the AD8608 op-amp used in the example circuit below.

This is being used as part of a dsp project and the recommended AD8606 is end of line from what I gather + way too expensive. I'll need 4 outputs hence the decision to use an op-amp with 14 pins.

Is anyone able to see any issues with my attempt?

Example circuit
Example filter circuit

Altered version


Thanks in advance


Joined Mar 14, 2008
I see no obvious problem with changing the op amp.
There may however, be a slight change in the filter response since you are going from a 10MHz to a 1MHz bandwidth op amp.

But is the DAC-Out signal positive since, with a single supply, the op amp output can only go positive?

Thread Starter


Joined Apr 16, 2022
Hi @crutschow , yes the DAC-out has a DC offset of 1.5V. Just to clarify, I plan to use the 14 pin LTC728 which looks to be 11MHz and not 1MHz or have I misinterpreted the datasheet?


Joined Aug 21, 2008
I hope you will be able to replace the opamp if it turns out that 11 MHz has insufficient gain-bandwidth for your application. It may help to roll off the DAC output with a passive RC filter first. A good SPICE simulation with a good model of the opamp would probably be helpful right now.