Why is a decoupling capacitor needed for TTL ICs and where should it be connected?
-
to block dc, connect to input pins -
to reduce noise, connect to input pins -
to reduce the effects of noise, connect between power supply and ground
How can ECL have both a NOR and an OR output?
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ECL does not have this feature. -
They are simply the inverse of each other.
The high input impedance of MOSFETs:
-
allows faster switching -
reduces input current and power dissipation -
prevents dense packing -
creates low-noise reactions
The output current capability of a single 7400 NAND gate when HIGH is called ________.
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source current -
sink current -
IOH -
source current of IOH
The TTL HIGH level source current is higher than the LOW level sinking current.
-
True -
False
The most common TTL series ICs are:
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E-MOSFET -
7400 -
quad -
AC00
Ten TTL loads per TTL driver is known as:
-
noise immunity -
fan-out -
power dissipation -
propagation delay
The word "interfacing" as applied to digital electronics usually means:
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a conditioning circuit connected between a standard TTL NAND gate and a standard TTL OR gate -
a circuit connected between the driver and load to condition a signal so that it is compatible with the load -
any gate that is a TTL operational amplifier designed to condition signals between NMOS transistors -
any TTL circuit that is an input buffer stage
Using the schematic diagram of a TTL NAND gate, determine the state of each transistor (ON or OFF) when all inputs are high.
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Q1-ON, Q2-OFF, Q3-ON, Q4-OFF -
Q1-ON, Q2-ON, Q3-OFF, Q4-OFF -
Q1-OFF, Q2-OFF, Q3-ON, Q4-ON -
Q1-OFF, Q2-ON, Q3-OFF, Q4-ON
Which logic family is characterized by a multiemitter transistor on the input?
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ECL -
CMOS -
TTL -
None of the above
The time needed for an output to change from the result of an input change is known as:
-
noise immunity -
fan-out -
propagation delay -
rise time
The problem of different current requirements when CMOS logic circuits are driving TTL logic circuits can usually be overcome by the addition of:
-
a CMOS inverting bilateral switch between the stages -
a TTL tristate inverting buffer between the stages -
a CMOS noninverting bilateral switch between the stages -
a CMOS buffer or inverting buffer
The rise time (tr) is the time it takes for a pulse to rise from its ________ point up to its ________ point. The fall time (tf) is the length of time it takes to fall from the ________ to the ________ point.
-
10%, 90%, 90%, 10% -
90%, 10%, 10%, 90% -
20%, 80%, 80%, 20% -
10%, 70.7%, 70.7%, 10%
If all inputs to a TTL NAND gate are low, what is the ON, OFF condition of each transistor in the circuit?
-
Q1-ON, Q2-OFF, Q3-ON, Q4-OFF -
Q1-ON, Q2-ON, Q3-OFF, Q4-OFF -
Q1-OFF, Q2-OFF, Q3-ON, Q4-ON -
Q1-OFF, Q2-ON, Q3-OFF, Q4-ON
The problem of the VOH(min) of a TTL IC being too low to drive a CMOS circuit and meet the CMOS requirement of VIH(min) is usually easily overcome by:
-
adding a fixed voltage-divider bias resistive network at the output of the TTL device -
avoiding this condition and only using TTL to drive TTL -
adding an external pull-down resistor to ground -
adding an external pull-up resistor to VCC
The problem of interfacing IC logic families that have different supply voltages (VCC's) can be solved by using a:
-
level-shifter -
tristate shifter -
decoupling capacitor -
pull-down resistor
The problem of the VOH(min) of a TTL IC being too low to drive a CMOS circuit and meet the CMOS requirement of VIH(min) is usually easily overcome by:
-
adding a fixed voltage-divider bias resistive network at the output of the TTL device -
avoiding this condition and only using TTL to drive TTL -
adding an external pull-down resistor to ground -
adding an external pull-up resistor to VCC
Fan-out is determined by taking the ________ result(s) of ________.
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smaller, 
-
larger, 
-
smaller, 
-
average, 
Which family of devices has the characteristic of preventing saturation during operation?
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TTL -
MOS -
ECL -
IIL
What is unique about TTL devices such as the 74SXX?
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These devices use Schottky transistors and diodes to prevent them from going into saturation; this results in faster turn-on and turn-off times, which translates into higher frequency operation. -
The gate transistors are silicon (S), and the gates therefore have lower values of leakage current. -
The S denotes the fact that a single gate is present in the IC rather than the usual package of 2–6 gates. -
The S denotes a slow version of the device, which is a consequence of its higher power rating.