Digital Electronics:: Logic Families and Their Characteristcs
Digital Electronics:: Logic Families and Their Characteristcs
21. 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%
22. The term buffer/driver signifies the ability to provide low output currents to drive light loads.
- TRUE
- FALSE
23. PMOS and NMOS ________.
- represent MOSFET devices utilizing either P-channel or N-channel devices exclusively within a given gate
- are enhancement-type CMOS devices used to produce a series of high-speed logic known as 74HC
- represent positive and negative MOS-type devices, which can be operated from differential power supplies and are compatible with operational amplifiers
- None of the above
24. Why is the operating frequency for CMOS devices critical for determining power dissipation?
- At low frequencies, power dissipation increases.
- At high frequencies, the gate will only be able to deliver 70.7 % of rated power.
- At high frequencies, charging and discharging the gate capacitance will draw a heavy current from the power supply and thus increase power dissipation.
- At high frequencies, the gate will only be able to deliver 70.7 % of rated power and charging and discharging the gate capacitance will draw a heavy current from the power supply and thus increase power dissipation.
25. Ten TTL loads per TTL driver is known as:
- noise immunity
- fan-out
- power dissipation
- propagation delay
26. 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
27. Totem-pole outputs ________ be connected ________ because ________.
- can, in parallel, sometimes higher current is required
- cannot, together, if the outputs are in opposite states excessively high currents can damage one or both devices
- should, in series, certain applications may require higher output voltage
- can, together, together they can handle larger load currents and higher output voltages
28. The high input impedance of MOSFETs:
- allows faster switching
- reduces input current and power dissipation
- prevents dense packing
- creates low-noise reactions
29. The output current capability of a single 7400 NAND gate when HIGH is called ________.
- source current
- sink current
- IOH
- source current of IOH
30. 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