Stats

  • Locked Locked
  • Replies 7
  • Subscribers 63
  • Views 16567
  • Members are here 0
This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

A tran simulation problem of RLC resonated network.

xxgenerall
Hi everyone,

A RLC resonant network is as Figure 1, seen at my post below.

L=1uH, C=1uF, R=100kOhms.

Source generates a sine wave signal. The source signal's frequency is 159.155kHz and its amplitude is 10V.

1. Theoretical analysis.

 The resonant frequency of LC network is about 159.155kHz. Under this frequency, the LC network's AC impedance is very large, and reaches about 1.5 MOhms. So if the circuit becomes steady, Vout is about 0V, whereas Vin-Vout is almost equal to Vin.

2. Tran simulation result.

A tran simulation is implemented with Cadence Spectre. The "stop time" is set to be 1s, so that the circuit can get steady. The tran simulation result is as Figure 2, seen at my post below.

It is seen that, Vout is almost equal to Vin.

By the way, sp and ac simulations are also carried out, which all indicate the LC network has a very large impedance at 159.155kHz.

The tran simulation result is so different from the theoretial analysis, and is not consistent with sp and ac simulation results. Why?

-----------------------------------------

Hi Mr. Beckett, Thanks for your help.
Parents

  • Hi Mr Beckett,

    Thanks for your help.

    After reading your advise, I carried out 2 simulations again.

    The first simulation is carried out with  maxstep=1/(100*159K), as the original simulation setting. And, the second simulation is set up with  maxstep=1/(2000*159K), following Mr Beckett's advice.

    The figure of simulation results is as below.

    It can be seen that, the simulation result is correct when maxstep=1/(2000*159K), and is wrong when maxstep=1/(100*159K).

    The symbols are all turn on in the simulation result figure. It is indicated that, there are enough points among each Vout period, regardless of the maxstep value. So, I can't understand why simulation results are so different under the condition of different maxstep values.

     

    Mr Beckett, could you help me please? Thank you very much.

Reply

  • Hi Mr Beckett,

    Thanks for your help.

    After reading your advise, I carried out 2 simulations again.

    The first simulation is carried out with  maxstep=1/(100*159K), as the original simulation setting. And, the second simulation is set up with  maxstep=1/(2000*159K), following Mr Beckett's advice.

    The figure of simulation results is as below.

    It can be seen that, the simulation result is correct when maxstep=1/(2000*159K), and is wrong when maxstep=1/(100*159K).

    The symbols are all turn on in the simulation result figure. It is indicated that, there are enough points among each Vout period, regardless of the maxstep value. So, I can't understand why simulation results are so different under the condition of different maxstep values.

     

    Mr Beckett, could you help me please? Thank you very much.

Children
No Data

Community Guidelines

The Cadence Design Communities support Cadence users and technologists interacting to exchange ideas, news, technical information, and best practices to solve problems and get the most from Cadence technology. The community is open to everyone, and to provide the most value, we require participants to follow our Community Guidelines that facilitate a quality exchange of ideas and information. By accessing, contributing, using or downloading any materials from the site, you agree to be bound by the full Community Guidelines.