Hello,

How can I generate waveforms like these in LTspice/PLECS? I am working on a Multilevel Buck Converter (aka FCML Buck/ Switched Capacitor Buck). The period is 10us. Each switch is ON for 2us. I have attached a picture of the circuit. Please share some valuable insight!

 

Just was a Piecewise Linear source for each signal.

 

Just was a Piecewise Linear source for each signal.

Hello, thank you for the response. I had used PWL source for each switch. The problem is, it's not holding the sequence. I have attached the ASC file for your reference. I was supposed to get 12V at the switching node, but it's 0. I am not sure how to make it work. Any kind of suggestion?

 

I should mention that LTSpice's PWL source doesn't automatically repeat, so you either need to define enough periods to last throughout the duration of your simulation (which you can do easily with a speadsheet and copying to a file), or you can use a behavioral to wrap a source back into the same period over and over.

 

Hello, thank you for the response. I had used PWL source for each switch. The problem is, it's not holding the sequence. I have attached the ASC file for your reference. I was supposed to get 12V at the switching node, but it's 0. I am not sure how to make it work. Any kind of suggestion?

I have no idea which node is "the switching node" or when it is supposed to have 12 V there.

Posting some simulation results and then referring to them in terms of what you expect them to do, what you need them to do, and what they are doing would help a lot.

 

I should mention that LTSpice's PWL source doesn't automatically repeat, so you either need to define enough periods to last throughout the duration of your simulation (which you can do easily with a speadsheet and copying to a file), or you can use a behavioral to wrap a source back into the same period over and over.

I am using the PWL this way. Do you think anything is wrong, or should I modify the logic here?

 

I should mention that LTSpice's PWL source doesn't automatically repeat, so you either need to define enough periods to last throughout the duration of your simulation (which you can do easily with a speadsheet and copying to a file), or you can use a behavioral to wrap a source back into the same period over and over.

I actually stand corrected. I forgot that you can manually at the repeat functionality to the PWL source in LTSpice, you just can't do it through the dialog.

PWL REPEAT FOREVER (0 0 50n 5 2u 5 2.005u 0 2.5u 0 2.505u 5 4.5u 5 5u 0 10u 0) ENDREPEAT

This is for your first waveform with 50 ns rise and fall times.

 

I am using the PWL this way. Do you think anything is wrong, or should I modify the logic here?

How do you plan to physically implement all of those signals in such a way that they are each referred to a different internal node in your circuit?

The typical way is to have all of the signals referred to a single common node (usually, but not necessary, the 0 V common reference node).