# Digital Electronics - Logic Families and Their Characteristics

### Exercise :: Logic Families and Their Characteristics - General Questions

16.

Which of the following summarizes the important features of emitter-coupled logic (ECL)?

 A. low noise margin, low output voltage swing, negative voltage operation, fast, and high power consumption B. good noise immunity, negative logic, high-frequency capability, low power dissipation, and short propagation time C. low propagation time, high-frequency response, low power consumption, and high output voltage swings D. poor noise immunity, positive supply voltage operation, good low-frequency operation, and low power

Explanation:

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17.

Why is a pull-up resistor needed for an open collector gate?

 A. to provide Vcc for the IC B. to provide ground for the IC C. to provide the HIGH voltage D. to provide the LOW voltage

Explanation:

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18.

Why is a pull-up resistor needed when connecting TTL logic to CMOS logic?

 A. to increase the output LOW voltage B. to decrease the output LOW voltage C. to increase the output HIGH voltage D. to decrease the output HIGH voltage

Explanation:

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19.

The word "interfacing" as applied to digital electronics usually means:

 A. a conditioning circuit connected between a standard TTL NAND gate and a standard TTL OR gate B. a circuit connected between the driver and load to condition a signal so that it is compatible with the load C. any gate that is a TTL operational amplifier designed to condition signals between NMOS transistors D. any TTL circuit that is an input buffer stage

Explanation:

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20.

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.

 A. 10%, 90%, 90%, 10% B. 90%, 10%, 10%, 90% C. 20%, 80%, 80%, 20% D. 10%, 70.7%, 70.7%, 10%