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how to determine the continuous time loop filter transfer function from discrete time loop transfer function.

Loop filter transfer function is

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If DAC is of NRZ type with 3 bit input how to get the transfer function in continuous domain? Can I use ZOH for a 3 bit DAC? Can I use MATLAB d2c command for this conversion?

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  • \$\begingroup\$ qph.ec.quoracdn.net/main-qimg-43f2d184991033bf5f3b30a1e7bab33e \$\endgroup\$ – Andy aka Jul 29 '17 at 9:29
  • \$\begingroup\$ Nope. Simple d2c command won't help. There is something called an Impulse Invariant transform that we need to do. Here is the reference specific to sigma delta - ieeexplore.ieee.org/document/7974157 Also, the loop filter transfer function differs with the DAC pulse type, delay as well. \$\endgroup\$ – sundar Jul 29 '18 at 8:41
  • \$\begingroup\$ Also, could you post the model of the sigma delta modulator in discrete time domain and the exact DAC pulse? I will try to convert to the continuous time domain and post answer if possible. \$\endgroup\$ – sundar Jul 29 '18 at 8:43

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