A simplified small-signal equivalent circuit of a BJT-based amplifier is given below.

The small-signal voltage gain  in  is _________.

The identical MOSFETs  and  in the circuit given below are ideal and biased in the saturation region.  and  have a transconductance  of 5 mS .

The input signals (in Volts) are:

The output signal  (in Volts) is __________.

A good transimpedance amplifier has

Negative feedback in a closed-loop control system DOES NOT

In the circuit shown, . Transistors  and  are identical. Assume that the thermal voltage  is 26 mV at. At the value of the voltage  (in mV) is _______.

A good current buffer has

For the amplifier shown in the figure, the BJT parameters are, β = 200, and thermal voltage. The voltage gain () of the amplifier is _______.         

 The feedback topology in the amplifier circuit (the base bias circuit is not shown for simplicity) in the figure is

 In the differential amplifier shown in the figure, the magnitudes of the common-mode and differential-mode gains are  and, respectively. If the resistance  is increased, then

A cascade connection of two voltage amplifiers A1 and A2 is shown in the figure. The open-loop gain, input resistance, and output resistance  for A1 and A2 are as follows:

A1:  = 10, = 10 kΩ, = 1 kΩ.

A2: = 5, = 5 kΩ, = 200 Ω.

The approximate overall voltage gain  is _________.

The desirable characteristics of a trans-conductance amplifier are

If the emitter resistance in a common-emitter voltage amplifier is not bypassed, it will

In a voltage-voltage feedback as shown below, which one of the following statements is TRUE if the gain k is increased?

In the circuit shown below, capacitors  and  are very large and are shorts at the input frequency.  is a small signal input. The gain magnitude  at 10 Mrad/s is        

In a transconductance amplifier, it is desirable to have

The input impedance  and the output impedance of an ideal trans-conductance (voltage controlled current source) amplifier are

The effect of current shunt feedback in an amplifier is to

In an ideal differential amplifier shown in figure, a large value of         

Voltage series feedback (also called series shunt feedback) results in

If the differential voltage gain and the common mode voltage gain of a differential amplifier are 48 dB and 2 dB respectively, then its common mode rejection ratio is        

An amplifier without feedback has a voltage gain of 50, input resistance of 1 KΩ and output resistance of 2.5 KΩ. The input resistance of the current-shunt negative feedback amplifier using the above amplifier with a feedback factor of 0.2, is

Three identical amplifiers with each one having a voltage gain of 50, input resistance of 1KΩ and output resistance of 250Ω, are cascaded. The open circuit voltage gain of the combined amplifier is        

In a negative feedback amplifier using voltage-series (i.e. voltage-sampling series mixing) feedback.
( and denote the input and output resistance respectively)

Three identical RC-coupled transistor amplifiers are cascaded. If each of the amplifiers has a frequency response as shown in Figure, the overall frequency response is as given in

In the differential amplifier of Figure, if the source resistance of the current source  is infinite, then the common-mode gain is

An amplifier with resistive negative feedback has two left half-plane poles in its open-loop transfer function. The amplifier        

For a feedback amplifier, the open loop transfer function has three poles at,  and . The low frequency open loop gain is 1000 and the feedback factor  is 1. Use Bode plots to determine the phase margin of the amplifier. Is the amplifier stable?

 Negative feedback in an amplifier

Crossover distortion behaviour is characteristic of

An amplifier has an open-loop gain of 100, an input impedance of , and an output impedance of. A feedback network with a feedback factor of 0.99 is connected to the amplifier in a voltage series feedback mode. The new input and output impedances, respectively, are

An amplifier is assumed to have a single pole high frequency transfer function. The rise time of its output response to a step function input is 35nsec. The upper -3dB frequency (in MHz) for the amplifier to a sinusoidal input is approximately at

The circuit of Figure is an example of feedback of the following type        

In a differential amplifier, CMRR can be improved by using an increased

From a measurement of the rise time of the output pulse of an amplifier whose input is a small amplitude square wave, one can estimate the following parameter of the amplifier:

A distorted sinusoidal has the amplitudes  of the fundamental, second harmonic, third harmonic … respectively. The total harmonic distortion is

The emitter coupled pair of BJT’s gives a linear transfer relation between the differential output voltage and the differential input voltage  only when the magnitude of  is less  times the thermal voltage, where  is

In a shunt-shunt negative feedback amplifier, as compared to the basic amplifier

A multistage amplifier has a low-pass response with three real poles at ,  and . The approximate overall bandwidth B of the amplifier will be given by

A cascode amplifier stage is equivalent to

Negative feedback in

(1) Voltage series configuration

(2) Current shunt configuration

(a) Increase input impedance

(b) Decrease input impedance

(c) Increases closed loop gain

(d) Leads to oscillation

In the cascade amplifier circuit shown in the figure is determine the values of ,  and  such that the quiescent current through the transistors is 1 mA and the collector voltages are  and , Take , transistor  to be high and base currents to be negligible.        

In the circuit shown in the given figure N is a finite gain amplifier with a gain of k, very large input impedance, and very low output impedance. The input impedance of the feedback amplifier with the feedback impedance Z connected as shown will be        

Match the following

(a) Cascode amplifier

(b) Differential amplifier

(c)  Darlington pair common emitter amplifier

(1) Does not provide current gain

(2) Is a wideband amplifier

(3) Has very low input impedance and very high current gain

(4) Has very high input impedance and very high current gain

(5) Provides high common mode voltage rejection

To obtain very high input and output impedances in a feedback amplifier, the mostly used is

A power amplifiers delivers 50 W output at 50% efficiency. The ambient temperature is 25°C. If the maximum allowable junction temperature is, then the maximum thermal resistance  that can be tolerated is _________.

An amplifier has an open-loop gain of 100, and its lower-and upper-cut-off frequency of 100 Hz and 100 kHz, respectively. A feedback network with a feedback factor of 0.99 is connected to the amplifier. The new lower and upper-cut-off frequencies are at _________Hz and ________MHz.

A class – A transformer coupled, transistor power amplifier is required to deliver a power output of 10 watts. The maximum power rating of the transistor should not be less than

In order to reduce the harmonic distortion in an amplifier, its dynamic range has to be increased. ( True=1,False=0)

A pulse having a rise time of 40nsec is displayed on a CRO of 12MHz bandwidth. The rise time of the pulse as observed on the CRO would be approximately equal to _______ns

Negative feedback in amplifiers

In a multi-stage R-C coupled amplifier the coupling capacitor

The bandwidth of an n-stage tuned amplifier, with each stage having a band width of B, is given by

In a transistor push-pull amplifier

The transistors in the differential amplifier shown in figure are identical with  and  ohms at 1mA collector current. The circuit has a Common Mode Rejection Ratio (CMRR) of 100.         

(a) What is the differential gain  of the circuit?

(b) What is the common mode gain of the circuit?

(c) If DC voltage of 1010 mV and 990 mV are allied to inputs 1 and 2 respectively with reference to ground, what will be the output voltage___mV?