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Regarding SP simulation for phase shifter (phase interpolator)

Jay815
Jay815 over 12 years ago
Dear all,

I would like to ask a question about S-Parameter (SP) simulation for phase shifter (phase interpolator) design. I am designing a 10GHz phase shifter using I/Q interpolation (so called, Cartesian phase shifter or phase rotator). In order to see the phase shift, I ran a transient simulation and it worked as expected.

However, when I ran a SP simulation, here is some simulation information,

  1. There are two phase shifters: One’s output is reference and the other’s output is phase shifted.
  2. The input port (port#1) generates an I signal, and the output ports (port#2 and port#3) are connected to output LC loads of two phase shifters. (Of course, I have one more input port for Q signal generation)
  3. In order to see the phase difference of two phase shifter outputs, I checked the phases of S21 and S31. However, the phase difference between S21 and S31 is almost zero, which is not what I expected.

Hence, I am wondering if I cannot see the phase difference of the phase interpolation circuit with SP simulation or not. If it is possible, I am wondering what I did wrong.

For your information, when I designed a LC passive phase shifter, a SP simulation in the same manner worked fine.

Could you please advise?

Thank you so much!

Regards,

Jay
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  • Andrew Beckett
    Andrew Beckett over 12 years ago

    Jay,

    For the first question, the "phase for Sinusoid" is only relevant when you are generating a sinusoid - so in large signal analyses such as tran. For sp analysis you are not generating a large signal sine wave, so this is not used.

    For the second question I am not the right person to ask - it's been a long time since I was last testing designs on the bench (18 years?) - apart from the odd hobby thing at home, and even then not sure I ever used a VNA.

    Regards,

    Andrew.

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  • Andrew Beckett
    Andrew Beckett over 12 years ago

    Jay,

    For the first question, the "phase for Sinusoid" is only relevant when you are generating a sinusoid - so in large signal analyses such as tran. For sp analysis you are not generating a large signal sine wave, so this is not used.

    For the second question I am not the right person to ask - it's been a long time since I was last testing designs on the bench (18 years?) - apart from the odd hobby thing at home, and even then not sure I ever used a VNA.

    Regards,

    Andrew.

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