Hi guys ....
In order to get a rail to rail output "Bootstrap capacitor" are used...
Is the 'bootstrapping concept' is to make the output voltage independent of R4 or the voltage across R4....????
The minimum voltage drop across R4 limits the output voltage rail to rail swing capability thus decrease amplifier efficiency...so R4 is divided into two parts ..across the lower resistor Ry a bootstrap capacitor is connected ...which do not let the voltage vary across Ry..whatever the opamp output is...ok
Now according to circuit analysis equation 1 tells that if R4 increases or VR4 increases ..then IL will decrease which will further decrease Vout..
Is the real requirement is to increase the voltage drop across Ry or to make R4 vanish(independent of Vout) from the equation 1...to make Vout to swing to rail limits..
Vcc = VR4 + Vbe + Vo = IR4 * R4 + Vbe + IL* RL ..
Also IR4 = IL/(β + 1).
IL = (Vcc - Vbe)/( RL + R4/(β + 1)) ----------------------------1
and
Vo_max = IL * RL (peak value)
please help....
In order to get a rail to rail output "Bootstrap capacitor" are used...
Is the 'bootstrapping concept' is to make the output voltage independent of R4 or the voltage across R4....????
The minimum voltage drop across R4 limits the output voltage rail to rail swing capability thus decrease amplifier efficiency...so R4 is divided into two parts ..across the lower resistor Ry a bootstrap capacitor is connected ...which do not let the voltage vary across Ry..whatever the opamp output is...ok
Now according to circuit analysis equation 1 tells that if R4 increases or VR4 increases ..then IL will decrease which will further decrease Vout..
Is the real requirement is to increase the voltage drop across Ry or to make R4 vanish(independent of Vout) from the equation 1...to make Vout to swing to rail limits..
Vcc = VR4 + Vbe + Vo = IR4 * R4 + Vbe + IL* RL ..
Also IR4 = IL/(β + 1).
IL = (Vcc - Vbe)/( RL + R4/(β + 1)) ----------------------------1
and
Vo_max = IL * RL (peak value)
please help....
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