Amplifiers: Specifications and External Characteristics

What is the defining characteristic of an inverting amplifier's voltage gain?

A noninverting amplifier has a voltage-gain magnitude of 40. If the input voltage is vi(t) = 0.2 sin(1000 pi t), what is the correct expression for the output voltage vo(t)?

In the voltage-amplifier model, what does the output resistance Ro account for?

What are the reductions in voltage at the input and output terminals of an amplifier due to finite input resistance and non-zero output resistance called?

An amplifier with an input resistance of 2 M-ohm and an output resistance of 2 ohm has an open-circuit voltage gain of 10000. It is driven by a source with 1 M-ohm internal resistance and connected to an 8-ohm load. What is the overall voltage gain from the source, Avs = Vo/Vs?

When two or more amplifiers are connected with the output of one feeding the input of the next, what is this connection called?

If two amplifiers are cascaded, with the first stage having a voltage gain of Av1 = 150 and the second stage having a voltage gain of Av2 = 50, what is the overall voltage gain of the cascade?

When creating a simplified model for a cascaded amplifier, what are the input resistance and output resistance of the overall cascade?

According to the power balance relationship for an amplifier, what must the sum of the input signal power (Pi) and the supply power (Ps) be equal to?

An amplifier is supplied with 1.5 A from a 15-V supply. The output signal power is 2.5 W and the input signal power is 0.5 W. What is the power dissipated in the amplifier?

What is the definition of amplifier efficiency, eta?

An audio amplifier supplies a 24 V rms signal to an 8-ohm load. Its power supply delivers 4 A at a voltage of 50 V. Neglecting input signal power, what is the efficiency of this amplifier?

Which amplifier model uses a current-controlled current source to represent the gain property?

An amplifier is modeled by a voltage-amplifier model with Ri = 1 k-ohm, Ro = 100 ohm, and Avoc = 100. What is the short-circuit current gain, Aisc, for its equivalent current-amplifier model?

An amplifier has an input resistance of 1 M-ohm, an output resistance of 10 ohm, and a short-circuit transconductance gain (Gmsc) of 0.05 S. What is the open-circuit transresistance gain (Rmoc) for this amplifier?

For an application like an electronic ammeter, which is inserted in series into a circuit to measure current, what is the desired input impedance for the amplifier?

In an application where an amplifier drives a light-emitting diode (LED) and the light intensity needs to be proportional to the current, what is the desired output impedance for the amplifier?

What are the input and output impedance characteristics of an ideal voltage amplifier?

What type of ideal amplifier has zero input impedance and infinite output impedance?

A transducer's short-circuit current is proportional to liquid level. An amplifier is needed to deliver a voltage signal proportional to this level to a resistive load that varies from 1 k-ohm to 10 k-ohm. What type of ideal amplifier is required?

What type of amplifier has constant gain down to zero frequency (DC)?

The input voltage to an amplifier is vi(t) = 0.1 cos(2000 pi t - 30 degrees) and the output is vo(t) = 10 cos(2000 pi t + 15 degrees). What is the complex voltage gain, Av?

What are the frequencies at which the voltage gain magnitude of an amplifier is 1/sqrt(2) times the midband gain magnitude called?

What is the term for an amplifier whose frequency response is deliberately limited to a small bandwidth compared with its center frequency?

What type of distortion occurs if the gain of an amplifier has a different magnitude for the various frequency components of an input signal?

An amplifier has a gain of 10 at 1000 Hz and a gain of 2.5 at 3000 Hz, both with zero phase shift. If the input is vi(t) = 3 cos(2000 pi t) - 2 cos(6000 pi t), what is the output vo(t)?

What condition must be met by an amplifier's phase response to avoid causing phase distortion?

What is the approximate relationship between the rise time (tr) and the half-power bandwidth (B) of a wideband amplifier?

A radar system needs to distinguish objects that are 10 meters apart, requiring a maximum amplifier rise time of 66.7 ns. Using the rule-of-thumb relationship, what is the minimum required bandwidth for the amplifier?

In the pulse response of an AC-coupled amplifier, what is the term for the droop or decay in the flat top of an output pulse?

An amplifier is needed to amplify pulses with a duration of 100 microseconds with a sag (tilt) of not more than 1 percent. What is the highest value allowed for the lower half-power frequency (fL) of the amplifier?

What is an amplifier's transfer characteristic?

If a sinusoidal signal is applied to the input of a nonlinear amplifier, what is the nature of the output signal?

An amplifier with a transfer characteristic of vo = 100vi + vi^2 receives a sinusoidal input vi(t) = cos(omega*t). What is the second-harmonic distortion factor, D2?

How is the Total Harmonic Distortion (THD), denoted by D, calculated from the individual harmonic distortion factors (D2, D3, etc.)?

What is the output voltage, vo, of an ideal differential amplifier with inputs vi1 and vi2, and a differential gain of Ad?

In a differential amplifier, how are the differential signal (vid) and the common-mode signal (vicm) defined in terms of the inputs vi1 and vi2?

What does the Common-Mode Rejection Ratio (CMRR) of a differential amplifier quantify?

A differential amplifier has a differential gain Ad of 50,000. When its inputs are tied together and a 1-V signal is applied, the output is 0.1 V. What is the CMRR in decibels?

An electrocardiograph amplifier has a differential gain of 1000. The input is a 1 mV peak differential signal and a 100 V peak common-mode signal. To keep the common-mode output contribution to 1 percent of the differential output, what is the minimum required CMRR in decibels?

In the DC model of a real differential amplifier, what are the small DC currents drawn by the internal circuitry through the input terminals called?

What is the primary method for mitigating the effects of input bias currents in a differential amplifier circuit?

A differential amplifier with a gain of 100 has its inputs connected to ground through 100 k-ohm resistors. It has a maximum input offset current of 80 nA and an input impedance of 1 M-ohm. What is the maximum output voltage caused by the offset current alone?

In a simplified model for a cascaded amplifier consisting of a first stage with Avoc1 = 200, Ro1 = 500 ohm and a second stage with Avoc2 = 100, Ri2 = 1500 ohm, what is the voltage gain of the first stage (Av1)?

The output of amplifier A is voA(t) = 30 cos(2000 pi t) - 10 cos(6000 pi t). The output of amplifier B is voB(t) = 30 cos(2000 pi t - 45 deg) - 10 cos(6000 pi t - 135 deg). The output of amplifier C is voC(t) = 30 cos(2000 pi t - 45 deg) - 10 cos(6000 pi t - 45 deg). Which amplifier exhibits phase distortion?

For what type of signal is it particularly important for an amplifier to be DC-coupled to preserve the signal's information content?

An amplifier has an output resistance of 1 M-ohm, an open-circuit transresistance gain of 100 M-ohm, and is cascaded with a second amplifier. The second amplifier has an input resistance of 50 ohm. What type of ideal amplifier does the first amplifier (Amplifier A) approximate?

An amplifier with an open-circuit voltage gain of 100 has its output voltage drop to 80 when connected to a 10 k-ohm load. What is the output resistance of the amplifier?

Which amplifier imperfection is primarily responsible for causing 'ringing' in the pulse response?

A differential amplifier with a differential gain of 500 has its two input terminals tied together. A 10-mV-rms input signal is applied to the tied inputs, resulting in a 20 mV-rms output signal. What is the common-mode gain of this amplifier?