Operational amplifier fundamentals (Test 15)

Practical op amps have an input impedance of

1 Mohms

In voltage followers, what percentage of the output is feed back to the input

100%

Which of the following is true of the noninverting summer?

All inputs are combined and then amplified

The inverting summing amplifier performs which function?

All of the above

The output of the noninverting amplifier

All of the above

Which statement about difference amplifiers is true?

All of the above

When configured for a gain of one, the non-inverting summing amplifier acts as

An averager

Voltage follower circuits are used

As buffer circuits

The summing junction of the inverting summer is

At virtual ground

What is another name for the voltage follower?

Both a. and b.

In a typical difference amplifier, signals are applied to which input?

Both inputs; neither are grounded

The gain of the noninverting amplifier

Can not be less than one

The output of a noninverting summing amplifier

Can not exceed the negative supply voltage

An unwanted signal present at both inputs of the difference amplifier is the

Common-mode input voltage

An op amp configured as an open-loop comparator

Compares a voltage with a reference

The purpose of hypothesis in an op amp comparator circuit is to

Decrease input sensitivity

If the feedback resistor of a noninverting amplifier is decreased, the gain

Decreases

In the inverting summing amplifier, feedback current is

Equal to the sum of the input currents

The gain-bandwidth product of the voltage follower is

Equal to the value in the specification sheets

To change a difference amplifier to an inverting summer

Ground the noninverting input

A fractional gain amplifier

Has an output magnitude that is less than the input magnitude

Inverting summing ampifiers

Have two or more inputs

Ideally, the voltage follower should have

High input and low output impedance

One advantage of the unity-gain amplifier over the gain-of-one amplifier is

Higher input impedance

If the value of an inverting amplifier input resistor were lowered, calculated gain would

Increase

The different operating modes of the inverting summing amplifier depend upon the

Input and feedback resistor values

Input bias current enters

Into both inputs of an op amp

The output of the inverting summer

Is a function of the combined input signals

Which of the following is not true of an inverting amplifier?

Is has low input impedance

You can eliminate output-offset voltage by

Offset nulling the device

In a sine wave to square wave inverter, threshold voltage is determined by:

Positive feedback

The closed-loop op amp configuration

Provides stability

For a typical difference amplifier. the polarity of the output depends upon the

Relationship of the noninverting input voltage to the inverting input voltage

Which operation is not possible for the noninverting summing amplifier

Scaling

The main feature of the difference amplifier is its ability to

Subtract and amplify two voltages

The point where two or more voltages or currents meet and combine is the

Summing point

When the input resistor of an inverting summer are equal to RF, Vo equals

The negative sum of the input voltages

The breakpoint frequency occurs when

The output voltage drops 3dB from the starting voltage

Each input of the inverting summing amplifier is multiplied by

The ratio of RF to the corresponding RIN

Which op amp constraints apply to the noninverting summer?

They all apply

Which statement about comparator circuits is false?

They can never saturate in the closed-loop form

The output of a difference amplifier is V2-V1. If the input signal are opposite in phase but equal in magnitude, the circuit output is

Twice the magnitude of the input signals and in phase with the *noninverting* input signal

Differential voltage is the voltage measured at the

Two input terminals

In a comparator circuit, a reference voltage is

Used as a trigger voltage

Slew rate is measured in

Volts per microsecond

In an inverting op amp configuration, the noninverting terminal is connected to the

circuit common

To increase the bandwidth of the inverting amplifier, decrease the

circuit gain

From the top view of a DIP, pin count is

counterclockwise

In the noninverting summing configuration, the inverting input is connected to

ground

Voltage comparators are typically used as

level detectors