electronrancher
Advanced Member level 1
The topic is Error-Feedback Sigma Delta, it's a pretty impressive topology but I can't get one working!!!
**broken link removed**
His theory is that if you have an L-th order sigma delta loop, the error feedback configuration is stable when the adder chain is L+1 bits wide.
I find this is not the case. Using any order sigma delta (I tried 2, 3, and 4th order) it is fairly easy to explode the loop. In fact, for many inputs the error feedback configuration is not at all stable - I am wondering if anyone has successfully implemented either a 4th order digital loop or any order error-feedback loop.
My transfer functions are as follows (I will abbreviate z-3 meaning z^-3)
Second order:
H(z) = 2*z-1 - z-2
Third Order:
H(z) = 3*z-1 - 3*z-2 + z-3
Fourth Order:
H(z) = 4*z-1 - 6*z-2 + 4*z-3 - z-4
Pretty strightforward - anyone worked on these topics?
**broken link removed**
His theory is that if you have an L-th order sigma delta loop, the error feedback configuration is stable when the adder chain is L+1 bits wide.
I find this is not the case. Using any order sigma delta (I tried 2, 3, and 4th order) it is fairly easy to explode the loop. In fact, for many inputs the error feedback configuration is not at all stable - I am wondering if anyone has successfully implemented either a 4th order digital loop or any order error-feedback loop.
My transfer functions are as follows (I will abbreviate z-3 meaning z^-3)
Second order:
H(z) = 2*z-1 - z-2
Third Order:
H(z) = 3*z-1 - 3*z-2 + z-3
Fourth Order:
H(z) = 4*z-1 - 6*z-2 + 4*z-3 - z-4
Pretty strightforward - anyone worked on these topics?