I have this question when reading the common-base amplifier.
http://www.allaboutcircuits.com/vol_3/chpt_4/7.html. Not sure
if someone else will have the same question.
Since there are no figure names in the page I am referring to
the third circuit in the page (May be it is a good idea to name figures)
http://www.allaboutcircuits.com/vol_3/chpt_4/7.html#03116.png
Let us calculate the currents for this circuit.
Assume Vin = 1.7
Ie = Ib+Ic - (1)
loop 1,0,2
1.7 = .7 + R1*Ie
1.7 = .7 + 100*Ie
Ie = 10 mA - (2)
loop 0,3,4,2,1
16.7 = 5000Ic + .7 +100Ie
16 = 5000Ic + 1
15 = 5000Ic
Ic = 3mA
Ib =7mA from (1) and (2)
I expect Ic to be much larger than Ib for a transistor because β should be
of order of 50 or 100. Did I miss something in my calcuation?
http://www.allaboutcircuits.com/vol_3/chpt_4/7.html. Not sure
if someone else will have the same question.
Since there are no figure names in the page I am referring to
the third circuit in the page (May be it is a good idea to name figures)
http://www.allaboutcircuits.com/vol_3/chpt_4/7.html#03116.png
Let us calculate the currents for this circuit.
Assume Vin = 1.7
Ie = Ib+Ic - (1)
loop 1,0,2
1.7 = .7 + R1*Ie
1.7 = .7 + 100*Ie
Ie = 10 mA - (2)
loop 0,3,4,2,1
16.7 = 5000Ic + .7 +100Ie
16 = 5000Ic + 1
15 = 5000Ic
Ic = 3mA
Ib =7mA from (1) and (2)
I expect Ic to be much larger than Ib for a transistor because β should be
of order of 50 or 100. Did I miss something in my calcuation?
