ECE 3201 - BJT
You can achieve a current gain greater than beta (T/F)
False
For a NPN transistor, it will be in forward active region if (?). What about PNP?
Forward active if Vce is greater than 0V but less than Vcc. (NPN) Forward active if Vce is less than 0V but greater than Vee (PNP)
Ratio of R1 and R2 (for design)
Vcc - (Ve + Vbe) / (Ve + Vbe)
What type of circuit is this?
Voltage Divider Bias
What type of circuit is this?
Voltage Feedback Bias
Voltage Swing and Current Swing
Voltage Swing = min {2(Vceq), 2(Vceo - Vceq)} Current Swing = Voltage Swing / RL
Common Base Bias
What type of circuit is this?
Emitter-Stabilized Bias
What type of circuit is this?
Fixed Bias
What type of circuit is this?
For an emitter follower, Ro is approximately equal to (?)
re
How do you find Ai1, Ai2, and AiT?
Ai1 = -Av1(Ri1 / Ri2) Ai2 = -Av2(Ri2 / RL) AiT = -AvT(Ri1/RL)
When considering a two cascaded amplifier, how do you find Av1? Av2? Avt? Avts?
Av1 = Avnl1 (Ri2 / Ri2 + Ro1) Av2 = Avnl2 (Rl / Rl + Ro2) Avt = Av1 * Av2 Avts = Avt * (Ri1 / Ri1 + Rsig)
Rank the voltage gain from least to greatest (with load and ac signal input, with load, without load)
Avs, Av, Avnl
Draw a CE amplifier with unbypassed RE ac small signal model
Draw
Draw a EF/CC ac small signal model
Draw
Draw a common base amplifier ac small signal model
Draw
Draw a fixed bias CE ac small signal model
Draw
Draw a voltage divider CE ac small signal model
Draw
The voltage divider bias circuit is the least susceptible to changes with respect to Beta (T/F)
True
AC Load Line
(Ic - Icq) = -1/(Rc || RL) * (Vce - Vceq)
What does it mean when transistor is at cutoff?
Currents are 0
Describe the voltage gain for common emitter, common base, and common collector
CE = high and inverting (-100) CB = high (100) CC = unity and inverting (-1)
Describe the input impedance for common emitter, common base, and common collector
CE = moderate (1k ohms) CB = low (10 ohms) CC = high (100k ohms)
Describe the output impedance for common emitter, common base, and common collector
CE = moderate (1k ohms) CB = moderate (1k ohms) CC = low (10 ohms)
What type of circuit is this?
Collector Feedback CE
What type of circuit is this? (Ignore R2)
Common Collector/Emitter Follower Amplifier
In a Q point graph, if you increase Ib, where would the Q point go? Increasing beta? Increasing Rc? Decreasing Vcc?
Q point will go upward, more to the left Q point will go upward, more to the left (depending on the beta value) Q point would shift downward, due to a new load line (y-intercept decreases) Q point would shift downward, where new line changes (shift downward)
A circuit is sensitive to beta if (?) A circuit is sensitive to Vbe if (?)
R1 + R2 (Rth) >> RE If both Rth and Re are small
For a NPN transistor, it will be in saturation if (?). What about PNP?
Saturated if Vce is less than 0V (NPN) Saturated if Vce is greater than 0V (PNP)
In a Q point graph, if a point is near the y-axis, what does that mean? What about x-axis?
Y-axis = limited voltage swing X-axis = limited current swing
Rank the circuit that is sensitive to beta from least to most (voltage divider, fixed bias, emitter stabilized)
voltage divider emitter stabilized fixed bias