Digital Electronics Flashcards
When is a BJT in forward active mode?
1) V(CE) > V(CE)sat
2) β*I(B) < I(C)sat
When is a BJT in Saturation mode?
1) V(CE) < V(CE)sat
2) β*I(B) > I(C)sat
When is a BJT in Cutoff mode?
1) β*I(B) = [I(C) <= 0]
2) V(CE) = V(CC)
How do you find the noise margins?
Find the expression for the base-emitter loop and substitute V(x) for V(in)
NM(0) = V(BE) - V(CE)
NM(1) = V(CC) - V(x)
What are the conditions for a DTL to have a logic 0?
When V(in) = 0; Diode 1 is on, Diode x and Q1 are off
What are the conditions for a DTL to have a logic 1?
V(in) = V(CC); Diode 1 is off, Diode x and Q1 are on
What should you try finding when in DTL logic 1?
The goal is to find R(A) and R(C) that puts the transistor in saturation mode
What should you do to improve the NM(0)?
Add more diodes after D(x)
What is fan out?
The maximum amount of gates able to be supported
Which number do you take for the fan-out?
The minimum if you have a number and infinity
How do you find the fan-out for an RTL circuit?
Develop a loop equation from the collector of the first RTL to the emitter of the second RTL when V(in) = 0
How do you find the fan-out of a DTL circuit?
Develop an expression for voltage at the input of the second DTL when the initial condition is a logic 1. Find all the currents in the first DTL and going into the input voltage node for the second DTL. Solve for N
What is I(C)sat in a DTL circuit?
The sum of the currents going into the Collector node labeled Q
