subh
12-17-2007, 05:33 AM
Hey guys,
I have a continuous-time sigma-delta converter that includes a
continuous-time transfer function H(s) at the input, followed by a
sampler, quantizer and a digital-to-analog converter (DAC) in the
feedback path. I'm trying to model the transfer function H(s) that
includes some non-ideal effects and hence, the order of H(s) is higher
than that of the system (say for the second-order system, I'm getting
a fourth-order H(s) term).
If I use simulink blocks to model this, the simulation speed is very
slow and it doesn't tend to converge. So, if anyone has modelled a
continuous-time transfer function using s-function blocks (I guess
writing C codes will speed it up), please suggest me how to design
it.
Matlab has an example in the sfundemos for continuous-time c-code
transfer function, but if I incorporate it, I initially get an input
port width error (for quantization levels exceeding 2) and hence,
either I need to use a quantizer with 2 levels or change the
inputPortWidth to "DYNAMICALLY SIZED" in the example code itself.
Any help will be great!
Thanks,
Subh.
I have a continuous-time sigma-delta converter that includes a
continuous-time transfer function H(s) at the input, followed by a
sampler, quantizer and a digital-to-analog converter (DAC) in the
feedback path. I'm trying to model the transfer function H(s) that
includes some non-ideal effects and hence, the order of H(s) is higher
than that of the system (say for the second-order system, I'm getting
a fourth-order H(s) term).
If I use simulink blocks to model this, the simulation speed is very
slow and it doesn't tend to converge. So, if anyone has modelled a
continuous-time transfer function using s-function blocks (I guess
writing C codes will speed it up), please suggest me how to design
it.
Matlab has an example in the sfundemos for continuous-time c-code
transfer function, but if I incorporate it, I initially get an input
port width error (for quantization levels exceeding 2) and hence,
either I need to use a quantizer with 2 levels or change the
inputPortWidth to "DYNAMICALLY SIZED" in the example code itself.
Any help will be great!
Thanks,
Subh.