Then there are those who only want Chips in their amp.
www.passlabs.com/np/GC-SS-4a.pdf
In this case the output stage consists of both series and parallel
chip amps. The voltage sources you see introduce differential
DC offset between the two parallel chip amps, which allows
a DC bias current for the amps which can be set arbitrarily.
This DC bias is not seen by the load which sits beween the
output resistors. The damping factor remains high, as it is
enclosed by the GC input pair.
I leave it to you to decide what constitutes an acceptable
bias current for the chip amps.
Like the other versions, note the chip amps each having their
own local (nested if you like) feedback loops. Adjusting these
loops will give a wide range of performance/stability character.
As with version 3, we can easily arrange to invert the input
pin polarities of the chip amps, but that would be a trivial
variation after the first example.
There will be a prize for the first person to find a mistake
in any of the four.
www.passlabs.com/np/GC-SS-4a.pdf
In this case the output stage consists of both series and parallel
chip amps. The voltage sources you see introduce differential
DC offset between the two parallel chip amps, which allows
a DC bias current for the amps which can be set arbitrarily.
This DC bias is not seen by the load which sits beween the
output resistors. The damping factor remains high, as it is
enclosed by the GC input pair.
I leave it to you to decide what constitutes an acceptable
bias current for the chip amps.
Like the other versions, note the chip amps each having their
own local (nested if you like) feedback loops. Adjusting these
loops will give a wide range of performance/stability character.
As with version 3, we can easily arrange to invert the input
pin polarities of the chip amps, but that would be a trivial
variation after the first example.
There will be a prize for the first person to find a mistake
in any of the four.
inverting topology
You need not give up.
As the 2nd OPA gets its inputsignal from the supply shunt resistor
of the first one the phase is 180°.
Imagine driving OPA1 with positive signal -> output gets positive
thus drawing current from PSU -> this in turn leads to more
voltage across that shunt -> this again leads to negative voltage
at the capacitor coupled input of the 2nd OPA -> Bingo!
Uli
jh6you said:Red.hot.chilly.pepper:
The 4 inside should have the flipped polarities. Otherwise, I give up this project...??? Because of.........................
You need not give up.
As the 2nd OPA gets its inputsignal from the supply shunt resistor
of the first one the phase is 180°.
Imagine driving OPA1 with positive signal -> output gets positive
thus drawing current from PSU -> this in turn leads to more
voltage across that shunt -> this again leads to negative voltage
at the capacitor coupled input of the 2nd OPA -> Bingo!
Uli
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