About dissipation of complementary bjts

[ginetto61]

Hi i have a question about dissipation of complementary bjts I have attached a circuit to explain my doubt
The npn Q3 on one side and the pnp Q4 on the other voltage side have very different dissipations Is it normal ?
I know it is a silly question but i was hoping that the symmetry would be maintained also in the dissipations
Is this normal ?
Thanks a lot
By the way if you have advices on the circuit i would very grateful

 

[peranders]

You could have a problem with connected the gates of the JFET's. You have no DC path there. The leakage currents must go somewhere.

 

[JMFahey]

Agree, those gates are open, no reference to ground.
Output will float anywhere
No symmetry possible except by chance.

 

[ginetto61]

Hi and thanks for the kind and valuable reply You mean a resistor to ground is missing ?
Moreover is it normal to have such difference in power dissipation between the two sides ? very different

 

[ginetto61]

Agree, those gates are open, no reference to ground.
Output will float anywhere
No symmetry possible except by chance.

Hi thanks a lot To be honest the original schematic is different ... i am trying to prune it to something more basic
I am fixated on unity gain devices mostly

 

[brian92fs]

Adding current's help to see what's going on. Here are the currents with and without a ground reference.

Also, matching devices will help to equalize things. The models used are likely not matched, though devices in the actual circuit may be matched.

 

[ginetto61]

Hi thanks a lot indeed ! i see in the 2nd case the currents are mirroring each other so much better indeed !
These fets are strange to me But i see that everyone love fets ...
I understand also that when the parts are matched the differences will be lower I read something about npn and pnp being intrinsecally different
From a structure point of view And this will reflect also on some parameters i guess
Any idea about how to lower the HD ? i have pruned the original schematic because i do not need gain