Why is this circuit used in power amplifiers?

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danesh

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hi,

Could anyone tell me why does this kind of circuit used to bias the non-inverting pin of and inverting amp. As i know it would provide 0.5Vcc to non inverting pin. Can we jus use dividing resistor. Why do this circuit is used often aspecially in power amp circuit ?
 

Re: Opamp biasing

This circuit provides virtual ground on its output pin. It is often used in OP Amp circuits with single supply voltage.
 

Re: Opamp biasing

This can be used for don't load the voltage divider ... as Borber says an be a virtual ground.


leomecma
 

Re: Opamp biasing

Resistor divider will have a higher output impedance. This circuit will have a low output impedance so it will be able to respond faster to changes in output of power amplifier (as this node will be coupled to output). So any changes in utput will affect this bias node also.
 

Opamp biasing

I think use the op, you can get the voltage of 6V and power driver,like a DC voltage. Using Resistor divider, you can get the voltage,but no driver
 

Re: Opamp biasing

Hi
I have doubt in this ,How will the Input common mode range of the opamp affects this specification.

Thanks

Prabhu.G
 

Re: Opamp biasing

Input Common Mode Voltage Range parameter is not exceeded in this case and circuit will work fine. Input voltage is half of the supply voltage.
 

Re: Opamp biasing



if you use the voltage divider to drive the resistor load, you won't be able to get the voltage 0.5vcc to drive the resitor load, the voltage will drop. But if you use the buffer in between, you can get voltage 0.5vcc to drive the resistor load because the buffer can sink more current and it is a negative feedback, the
output will very stable with low output impedance.
 

Opamp biasing

the resistor divider set a certain voltage which is copied than (inDC) to the output
 

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