Hi all, i have a question concerning q points and a stabilised bias circuit.
Q. Draw the subcircuit that is relevant for evaluating the dc currents and voltages and proceed to derive an equation for the load line.
My attempt for the sub-circuit is attached, i think the capacitors act as an open circuit at dc, which is how i arrived at that result, but i am not sure if this what the question was asking me to do.
The main problem i have is trying to derive the equation for the load line, my attempt at this part of the question is below:
Vcc=I1.R1+VBE+IE.RE
I2=(VBE+IE.RE)/R2
I1=I2+(IC/β)
These equations can be re-arranged to find:
Vcc=((VBE+IE.RE/R2)+(IC/β)).R1+VBE+IE.RE
The equation IE=IC(1+(1/β)) can be used to eliminate IE.
I eventually got an equation of VCC=VBE(R1+R2/R2)+IC.RE(R1+R2/R2), by somehow eliminating β from the equation, this doesnt seem to give me an equation i can use for a load line, so any help would be appreciated just to let me know if i am going in the correct direction or not and whether this equation is even close to being able to create a load line.
thanks
bob12
Q. Draw the subcircuit that is relevant for evaluating the dc currents and voltages and proceed to derive an equation for the load line.
My attempt for the sub-circuit is attached, i think the capacitors act as an open circuit at dc, which is how i arrived at that result, but i am not sure if this what the question was asking me to do.
The main problem i have is trying to derive the equation for the load line, my attempt at this part of the question is below:
Vcc=I1.R1+VBE+IE.RE
I2=(VBE+IE.RE)/R2
I1=I2+(IC/β)
These equations can be re-arranged to find:
Vcc=((VBE+IE.RE/R2)+(IC/β)).R1+VBE+IE.RE
The equation IE=IC(1+(1/β)) can be used to eliminate IE.
I eventually got an equation of VCC=VBE(R1+R2/R2)+IC.RE(R1+R2/R2), by somehow eliminating β from the equation, this doesnt seem to give me an equation i can use for a load line, so any help would be appreciated just to let me know if i am going in the correct direction or not and whether this equation is even close to being able to create a load line.
thanks
bob12
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