Hi,

Can anyone please tell me the "maximum frequency range" up to which the LTspice simulator can be used? For example, can I use it for GHz range circuit simulations?

Regards
HARI

 

hi HARI,
What are you planning regarding a project.?
E

 

Hi Eric,

Thank you very much.
This is not specific to any project.

Just for curiosity ,I want to know what frequency LTSPICE can support.

Regards
HARI

 

LT Spice does not have a frequency limit per se.
The frequency limit depend more on the models you use. At very high frequencies LTSPICE will give you a solution, but the underlying models of the parts you chose might be wrong at these frequencies.

 

The sine voltage source seems quite happy at 1000 GHz. So no obvious practical limit.
Experiment for yourself.

 

LTspice depends on lumped parameter models. As such the practical frequency limit is determined by the necessity to switch from lumped parameter models to distributed parameter models. This happens when the wavelength of the signals approaches the physical dimensions of the circuit. Since LTspice does not have this physical limitation, it will give you a solution. As others have said it may not correspond to any actual reality.

If you are working in the VHF region and above, you might want to consider other alternatives.

 

Parts are complex. A simple resistor has a small amount of capacitance. A cap has resistance and several different types if resistance. All parts have inductor in the leads. (even surface mount resistors). Traces have inductance, capacitance and resistance. Capacitors have a resonant frequency.
At high frequencies I must watch all these hidden values. SPICE can help with that.

 

Hi,

Can anyone please tell me the "maximum frequency range" up to which the LTspice simulator can be used? For example, can I use it for GHz range circuit simulations?

Regards
HARI

In one regard, frequency is arbitrary -- as long as your time step is sufficiently small compared to the frequency, life is good. On paper.

But there are subtler details that can raise their ugly heads. At some point you run into finite precision limits and cumulative roundoff errors. These depend on the nature of the circuit/simulation and what is and is not important. They can actually be an issue even near DC, but tend to rear their heads at higher frequencies.

But, as already pointed out, the big issue for most high-frequency simulations is the ability to get (or develop) device and circuit models that sufficiently capture the parameters, such as parasitics, that are important for the real circuit in the real world. If you do a good enough job of modeling, then the simulator capabilities are unlikely to be an issue.