Hello,
this is my first post here. We use KiCad 5.1.12 at school but I also have the exact same problem in 8.0.6
The following push-pull amplifier simulation works well in DC and Transient analysis,
I cannot perform an AC analysis (Bode) in which i receive a spice message:
doAnalyses: matrix is singular
run simulation(s) aborted
I’ve tried setting initial values to capacitors, setting another component and input Vgen and
a ton of other methods, nothing works.
Any idea would be helpful.
Some more experimenting may be needed.
You have some extra dots near Vb1 and Vb2 and in the ground symbol. Try to remove them.
Put a resistor from Vin to ground.
Your VSIN source looks odd. I’m no expert, but mine looks like this:
dc=0 ampl=4 f=1k ac=1
The “ac=1” part allows you to do frequency sweeps (Bode).
I finally got it working by changing the transistor devices to generic NPN_CBE and PNP_CBE with the same spice LIBs. This is odd, since the dc and transient simulations worked fine with the previous model.
Anyway, I learned my lesson, BJTs to be used now are the above CBE ones, so they are both compatible with the .LIB model and the ac simulatorsl.
Thanx
I’m curious, could you post the .lib files?
Hi! I faced a similar issue where the simulation worked fine in DC and Transient analyses but failed during AC analysis with a singular matrix error. In my case, the problem was due to incomplete parameters in the transistor models.
Here’s how I resolved it:
Replaced the transistors with generic SPICE-compatible models like NPN_CBE and PNP_CBE.
Reviewed the .lib file to check key parameters, especially capacitances and gain coefficients.
Added resistors to floating nodes, such as between the base and emitter, which often stabilizes the circuit.
Double-checked all connections to ensure there were no mistakes.
To better understand the underlying issues, revisiting the basics of transistors and frequency response can be very helpful. For instance, video lectures on physics and electronics, on sites like LearnersTV physics courses, can clarify concepts like amplifier behavior in the frequency domain. Hope this helps!
