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zvcvs parameters for S&H, in ac, implementation

agaurav

Hi,

I want to make an ac model which has got sample and hold (zero-order). I found the block, zvcvs, for that. Can somebody suggest the suitable parameters' values to implement that.

I tried Polynomial argument = z or inversez

S to Z Transformation = default (I assume it means none)

Specification type = polynomial

And then I tried various polynomails (order 1 or 2) to get sample-and-hold fft output for a simple wideband spectrum signal-input but seems I am doing something somewhere wrong. I am not very good at digital and z and bilinear transforms, so I think the capability is there but somehow I am not able to implement it using zvcvs. Can somebody please help me with it - implementing sample and zero-order hold using zvcvs. 

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  • agaurav
    Hi Andrew, Thanks for your response. As usual, with many cases in past, you have come to the rescue. What I am looking for is a block which outputs the fourier-transform of the signal when the signal goes through that sample and hold circuit with clock frequency as the input parameter to the S&H block., in AC noise simulations. I have already tried what you suggested in zvcvs but the response doesn't seems to be in alignment with my expectation. If this block is not supposed to work in AC simulations, I'll expect it to flag and error, not some incorrect result. So, probably, it works in AC sims. But I am not sure if I want an output of signal G(s) going through H(z) and then look at its AC output (say some F(s)), should I select none/forward/backword/bilenar for S to Z Transformation parameter input. I have tried few zero-order hold possible options (I want to implement Zero-order hold by H(z) which I want to use zvcvs for) like z+1/z-1 and simple 1/z but noe of them give output as I desire/expect. I just want to know where am I going wrong. A bit more detailed document about this block will be extremely helpful I also had another problem of generating a noise source with logarithmic interpolation which I found a solution to using noise-source with 2 frequency-noise paris and passing ti through a svcvs which has pole-zero as specification type. So, this is the last bit I need to complete my model I am trying to build.
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  • agaurav
    Hi Andrew, Thanks for your response. As usual, with many cases in past, you have come to the rescue. What I am looking for is a block which outputs the fourier-transform of the signal when the signal goes through that sample and hold circuit with clock frequency as the input parameter to the S&H block., in AC noise simulations. I have already tried what you suggested in zvcvs but the response doesn't seems to be in alignment with my expectation. If this block is not supposed to work in AC simulations, I'll expect it to flag and error, not some incorrect result. So, probably, it works in AC sims. But I am not sure if I want an output of signal G(s) going through H(z) and then look at its AC output (say some F(s)), should I select none/forward/backword/bilenar for S to Z Transformation parameter input. I have tried few zero-order hold possible options (I want to implement Zero-order hold by H(z) which I want to use zvcvs for) like z+1/z-1 and simple 1/z but noe of them give output as I desire/expect. I just want to know where am I going wrong. A bit more detailed document about this block will be extremely helpful I also had another problem of generating a noise source with logarithmic interpolation which I found a solution to using noise-source with 2 frequency-noise paris and passing ti through a svcvs which has pole-zero as specification type. So, this is the last bit I need to complete my model I am trying to build.
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