GATE ECE
Analog Circuits
Bipolar Junction Transistor
Previous Years Questions

Marks 1

Resistor R1 in the circuit below has been adjusted so that I1 = 1 mA. The bipolar transistor Q1 and Q2 are perfectly matched and have very high curren...
Consider the circuit shown in the figure. Assuming VBE1 = VEB2 = 0.7 volt, value of the dc voltage Vc2 (in volt) is _______ ...
If the emitter resistance in a common-emitter voltage amplifier is not bypassed, it will
In the circuit shown, the PNP transistor has $$\left|{\mathrm V}_\mathrm{BE}\right|=0.7\;\mathrm V$$ and β = 50. Assume that RB = 100 kΩ. For V0 to be...
A cascade connection of two voltage amplifiers A1 and A2 is shown in the figure. The open-loop gain Av0, input resistance Rin, and output resistance R...
The current ib through the base of a silicon npn transistor is $$1\;+\;0.1\;\cos\left(10000\;\mathrm\pi\;\mathrm t\right)$$ mA . At 300 K, the $$r_\ma...
In the circuit shown below, capacitors C1 and C2 are very large and are shorts at the input frequency. Vi is a small signal input. The gain magnitude...
In the silicon BJT circuit shown below, assume that the emitter area of transistor Q1 is half that of transistor Q2.The value of current I0 is approxi...
The amplifier circuit shown below uses a silicon transistor. The capacitors CC and CE can be assumed to be short at signal frequency and the effect of...
The input impedance (Zi) and the output impedance (Zo) of an ideal transconductance (voltage controlled current source) amplifier are...
The cascode amplifier is a multistage configuration of
Assuming VCesat=0.2V and β = 50, the minimum base current (IB) required to drive the transistor in the figure to saturation is ...
The current gain of a BJT is
Introducing a resistor in the emitter of a common amplifier, stabilizes the dc operating point against variations in
The emitter coupled pair of BJT’s gives a linear transfer relation between the differential output voltage and the differential input voltage Vid only...
The circuit of Fig. is an example of feedback of the following type ...
From a measurement of the rise time of the output pulse of an amplifier whose input is a small amplitude square wave, one can estimate the following p...
In a series regulated power supply circuit, the voltage gain Av of the ‘pass’ transistor satisfies the condition:
A BJT is said to be operating in the saturation region if
A transistor having $$\alpha$$ = 0.99 and VBE = 0.7 V, is used in the circuit of the figure.What is the value of the collector current? ...
In order to reduce the harmonic distortion in an amplifier, its dynamic range has to be _________
A common emitter transistor amplifier has a collector current of 1.0 mA when its base current is 25 $$\mu$$A at the room temperature. It's input ...
For the amplifier circuit of figure, the transistor has a $$\mathrm\beta$$ of 800. The mid-band voltage gain $$V_0/V_1$$ of the circuit will be ...
The bandwidth of an n-stage tuned amplifier, with each stage having a band width of B, is given by

Marks 2

For the DC analysis of the Common-Emitter amplifier shown, neglect the base current and assume that the emitter and collector current are equal. Given...
In the figure shown, the npn transistor acts as a switch. For the input vin(t)as shown in the figure, the transistor switches between the cut-off a...
In the circuit shown, transistors Q1 and Q2 are biased at a collector current of 2.6 mA. Assuming that transistor current gains are sufficiently large...
In the ac equivalent circuit shown, the two BJTs are biased in active region and have identical parameters with β >> 1. The open circuit small ...
In the circuit shown, I1 = 80 mA and I2 b= 4mA. Transistors T1 and T2 are identical. Assume that the thermal voltage VT is 26 mV at 27oC. At 50oC, th...
Consider the common-collector amplifier in the figure (bias circuitry ensures that the transistor operates in forward active region, but has been omit...
A BJT in common-base configuration is used to amplify a signal received by a $$50\,\Omega $$ antena. Assume kT/q = 25 mV. The value of the collector ...
For the common collector amplifier shown in the figure, the BJT has high $${V_{CE\left( {sat} \right)}},$$ and $${V_{BE}}$$ $$\, = \,\,0.7\,\,\,V$$. ...
In the circuit shown, the silicon BJT has $$\beta \,\,\,\,50.\,\,\,\,\,$$ Assume $${V_{BE}}\,\,\, = \,\,\,0.7$$ and $${V_{CE\left( {sat} \right)}}\, =...
A BJT is baised in forward active mode Assume VBE = 0.7 V, kT/q = 25 mV and reverse saturation current Is = 10-13A. The transconductance of the BJT (i...
For the amplifier shown in the figure, the BJT parameters are VBE = 0.7 V, $$\beta $$ = 200, and thermal voltage VT = 25 mV. The voltage gain (Vo/Vi ...
In the circuit shown below, the silicon npn transistor Q has a very high value of $$\beta $$. The required value of R2 in k$$\Omega $$ to produce Ic ...
The voltage gain Av of the circuit shown below is ...
For a BJT, the common-base current gain $$\alpha = \,\,0.98$$ and the colector base junction reverse bias saturation current Ico = 0.6 $$\mu {\rm A}$...
For the BJT Q1 in the circuit shown below, $$\beta = \infty ,\,\,\,\,{V_{BEon\,}}\, = \,0.7V,\,\,\,{V_{CEsat}}\, = \,0.7V.$$. The switch is initially...
A small signal source Vi(t) = A cos 20t + B sin 106 t, is applied to a transistor Amplifier as shown in fig. The transistor has $$\beta $$ = 150 and h...
In the following transistor circuit, VBE = 0.7V, re = 25m/IE, $$\beta $$ and all the capacitances are very large. The Value of DC current IE is ...
In the following transistor circuit, VBE = 0.7V, re = 25m/IE, $$\beta $$ and all the capacitances are very large. The mid-band voltage gain of t...
In a transconductance amplifier , it is desirable to have
For the BJT circuit shown, assume that the $$\beta $$ of the transistor is very large and VBE = 0.7 V. The mode of operation of the BJT is ...
In the transistor amplifier circuit shown in the figure below, the transistor has the following parameters: $${\beta _{DC}}$$ = 60, $${V_{BE}}$$ = ...
In the transistor amplifier circuit shown in the figure below, the transistor has the following parameters: $${\beta _{DC}}$$ = 60, $${V_{BE}}$$ = ...
In the transistor amplifier circuit shown in the figure below, the transistor has the following parameters: $${\beta _{DC}}$$ = 60, $${V_{BE}}$$ = ...
The circuit using a BJT with β = 50 and VBE = 0.7 V is shown in the figure. The base current IB and collector voltage VC are respectively ...
For an npn transistor connected as shown in the figure, VBE = 0.7 volts. Given that reverse saturation current of the junction at room temperature $${...
A bipolar transistor is operating in the active region with a collector current of 1mA. Assuming that the 'β' of the transistor is 100 and the transco...
In the amplifier circuit shown in the figure, the values of R1 and R2 are such that the transistor is operating at VCE = 3V and IC = 1.5 mA when its $...
Three identical amplifiers with each one having a voltage gain of 50, input Resistance of 1 KΩ and output resistance of 250Ω, are cascaded. The open c...
In the circuit shown in the figure assume that the transistor is in the active region. It has a large β and its base Emitter voltage is 0.74. The valu...
A Darlington stage is shown in the figure, if the transconductance of q1 is gm1 and q2 is gm2, then the overall transconductance $$g\matrix{ c \cr...
Match the following. Group - I (a)Cascode amplifier (b)Differential Amplifier (c)Darlington pair common-collector Amplifier Group - II (1)does not pro...
If the transistors in fig. has high value of β and a vBE of 0.65, the current I flowing through the 2 kilo ohms resistance will be ______. ...
In figure, all transistors are identical and have a high value of beta. The voltage VDC is equal to ______. ...
Which of the following statements are correct for basic transistor Amplifier configurations?
For good stabilized biasing of the transistor of the CE Amplifier of fig, we should have ...
Of the four biasing circuits shown in Fig. For a BJT, indicate the one which can have maximum bias stability:
Each transistor in the Darlington pair (see Fig. below) has hfe = 100. The overall hfe of the composite transistor neglecting the leakage current is ...
The quiescent collector current Ic, of a transistor is increased by changing resistance. As a result
The amplifier circuit shown below uses a compostie transistor of a MOSFET and BIPOLAR in cascade. ALL capacitance are large. gm of the MOSFET = 2 mA/V...
The transistor in the amplifier shown below has following parameters: $$${h_{fe}}\, = \,100,\,{h_{ie}}\, = \,2k\Omega ,\,{h_{re}}\, = \,0,$$$ $${h_{o...

Marks 5

An emitter-follower amplifier is shown in the figure, Zi is the impedance looking into the base of the transistor and Z0 is the impedance looking into...
For the amplifier of given figure,$${I_C}\, = \,1.3\,mA,\,{R_C}\, = \,2\,k\Omega ,\,{R_E}\, = \,500\,\Omega ,$$ $${V_T}\, = \,26\,mV,\,\beta \, = \,1...
A bipolar junction transistor amplifier circuit is shown in the figure. Assume that the current source Ibias is ideal, and the transistor has very la...
In the circuit of fig. Determine the resistance Ro seen by the output terminals, ignore the effects of R1 and R2. ...
The transistor in the circuit shown in the figure. is so biased (dc biasing N/W is not shown) that the dc collector current IC = 1mA. Supply is VCC = ...
In the cascade amplifier circuit shown below, determine the values of R1, R2 and RL. Such that the quiescent current through the transistors is 1mA an...
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