Does it matter? (CLG/OLG question)

[Neutrality]

I have an amplifier design with a closed loop gain that reaches unity gain at about 5.5 MHz but the open loop gain reaches unity gain at about 1.5 MHz.

Does it matter that it runs out of OLG before the CLG reaches unity gain?

It is way out of the audible band and the OLG stays above the CLG until about 50 KHz so it shouldnt affect the sound quality of the amplifier.

[wahab]

Unity gain should be almost the same wether it is in respect of OLG or CLG.

Without curves and schematic , we can have no accurate idea
about what is going on.

[Neutrality]

Attahced are Schematic, CLG, OLG

[wahab]

The 1K TMC resistor should be connected to the output , not to the inverting input,
for OLG/CLG computations.

[Neutrality]

Originally Posted by wahab

The 1K TMC resistor should be connected to the output , not to the inverting input,
for OLG/CLG computations.

You sure about that?

[Neutrality]

Originally Posted by wahab

The 1K TMC resistor should be connected to the output , not to the inverting input,
for OLG/CLG computations.

Ehm, after trying that I'm quite sure that cant be right.

OLG drops to about 20 dB at 20 KHZ, that can not be right, THD-20 is incredibly low, about 0.007XX% at 60 Watt out in an 8 Ohm load. That doesnt look like only 20 dB OLG at 20 KHz......

EDIT : Think you havent looked closely at the schematic, the TMC resistor is not connected directly to the inverted input but before the 21K5 resistor in the 1K/21K5 gain setting resistors.

EDIT 2 : looking at the schematic, what I tried was connecting it after V6, that is on the A side instead of originally on the B side of V6. B side should be the right way, between 21K5 and B.

[wahab]

To compute the OLG , connect the TMC resistor to the input
and then add a very large inductance (10^15 H) in serial
with the feedback resistor AND lead capacitance.
The voltage source connected in serial with the feedback path
is to be removed with such protocol.

[Neutrality]

Originally Posted by wahab

To compute the OLG , connect the TMC resistor to the input
and then add a very large inductance (10^15 H) in serial
with the feedback resistor AND lead capacitance.
The voltage source connected in serial with the feedback path
is to be removed with such protocol.

TMC to input of what? The inverting input ? Or the input of the inductance in series with the feedback resistor/lead comp. cap?

[Neutrality]

Like this?

[wahab]

Originally Posted by Neutrality

Like this?

That s it , it should work , just increase the value to 10^15 H
so the lower frequency range wont be truncated at all.
10^15 = 1000000000000000