## Electronic Devices and Circuits 2 - Dec 18

### Electronics Engineering (Semester 4)

Total marks: 80

Total time: 3 Hours
INSTRUCTIONS

(1) Question 1 is compulsory.

(2) Attempt any **three** from the remaining questions.

(3) Draw neat diagrams wherever necessary.

**1.Attempt any four of the following:**

**1.a.**Explain high frequency equivalent circuit of BJT.

**1.b.**Explain Barkhausen criteria

**1.c.**Draw MOSFET differential amplifier with active load.

**1.d.**Calculate max. power dissipation with and without heat sink.

$\theta$ $ J_C$ = $1.75^o$ C/W , $\theta$ cs = $1^o$ C/W , $\theta_C$A = $50^o$ C/W

$\theta$ SA = $5^o$ C/W , $T_j max$ = $150^o$ C and TAmb = $30^o$ C

**1.e.**Explain PNPN diode.

**2.a.**Explain class B push pull amplifier and cross over distortion also derive expression for efficiency.

**2.b.**Explain small signal analysis for MOSFET active load circuit.

**3.a.**Calculate lower cut off frequency for given circuit.

$β $ = 80 , $r_π$ = 1.3 K Ω ,$ g_{m2}$ = 50 μ A/V , $C_π$ = 15pF , $C_μ$ = 1pF

**3.b.**Explain working of SCR with V-I characteristics and its applications.

**4.a**Explain Hartley oscillator. Design the same for 50KHz

**4.b.**Find $ I_Q$ for given circuit.

$K_{n1}$ = $K_{n2}$=0.1 mA/V2 , $K_{n3}$=$K_{n4}$=0.3mA/V2 , $V_{TN}$= 1 V,

$\lambda$ = 0 for M1 , M2 , M3 and $\lambda$= 0.01/V for M4

**5.a.**Calculate bandwidth for two stage RC coupled CE amplifier.

$\beta_1$ = 100, $\beta_2$ = 150 , $r_{π1}$ = $r_{π2}$ = 1.3 KΩ , $g_{m1}$ = $g_{m2}$ = 50mA/V

$C _{π1}$ = $C_{π2}$ = 15 pF, $C_{μ1}$ = $C_{μ 2}$ = 1 pF

**5.b.**Explain feedback topologies with the help of neat block diagram.

**6. Write short notes on: [ANY THREE]**

**6.a.**Cascode MOSFET amplifier

**6.b.**UJT relaxation oscillator

**6.c.**Darlington configuration

**6.d.**Power BJTs