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One testbench for PSS and Transient Simulation with different stimuli.

Thomas T

Hi,

 I am trying to setup an all-purpose testbench for some amplifier circuits I need on a regular basis that can be used for all the simulations I normaly use: DC, AC, TRAN and PSS.

 The problem I have stems from the fact, that I need to test my circuit in a pulsed operating mode in the transient simulation: the circuit has a node called "powerdown" which is driven by a VPWL voltage source. This activates and deactivates the circuit for a certain amount of time, allowing me to observe the transient behaviour of the circuit with regards to settling time etc. in a pulsed operating mode.

For my PSS simulations, where I want to establish the 1dB-compression point for example, the powerdown-node needs to be set to a defined voltage, in my case 0 volt (or connected to ground) in order to avoid the frequency components of the powerdown source. Is there a way, to setup both in one testbench ? For DC-simulations, I can just set the DC value of the vwpl source to 0 and everything works as expected. I haven't found a way to do the same for PSS simulations which leads to me always having to make a copy of the testbench where I then statically connect the powerdown node to ground. This has lead to mistakes in the past and I would prefer a single testbench that just works and can be reused.

 Thanks !

Parents

  •  Dear Thomas,

    > . Is there a way, to setup both in one testbench ? For DC-simulations, I can just set the DC value

    > of the vwpl source to 0 and everything works as expected. I haven't found a way to do the same for

    > PSS simulations which leads to me always having to make a copy of the testbench where I then

    > statically connect the powerdown node to ground. This has lead to mistakes in the past and I would

    > prefer a single testbench that just works and can be reused.

     

    I had a thought that I often use in my test benches to allow them to be used for many analysese that might be helpful and allow you to use the same test bench for a PSS simulation. When there are multiple stimuli, I include a design variable for each source to define its delay. For example, in your test bench with a powerdown piecewise linear source, I might invlude a delay variable "delay_powerdown" in the definition of the source as shown in the attached example. In your pss simulation, if the value of delay_powerdown is set to a value that far exceeds the value of TSTAB,  the source will remain at 0 throughout your PSS simulation. For a transient simulation, you might set delay_powerdown to something less than the TSTOP time of your simulation to study the impact of powerdown.

    I hope I understood your queston!

    Shawn

Reply

  •  Dear Thomas,

    > . Is there a way, to setup both in one testbench ? For DC-simulations, I can just set the DC value

    > of the vwpl source to 0 and everything works as expected. I haven't found a way to do the same for

    > PSS simulations which leads to me always having to make a copy of the testbench where I then

    > statically connect the powerdown node to ground. This has lead to mistakes in the past and I would

    > prefer a single testbench that just works and can be reused.

     

    I had a thought that I often use in my test benches to allow them to be used for many analysese that might be helpful and allow you to use the same test bench for a PSS simulation. When there are multiple stimuli, I include a design variable for each source to define its delay. For example, in your test bench with a powerdown piecewise linear source, I might invlude a delay variable "delay_powerdown" in the definition of the source as shown in the attached example. In your pss simulation, if the value of delay_powerdown is set to a value that far exceeds the value of TSTAB,  the source will remain at 0 throughout your PSS simulation. For a transient simulation, you might set delay_powerdown to something less than the TSTOP time of your simulation to study the impact of powerdown.

    I hope I understood your queston!

    Shawn

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