Question I: Multiple choice

$(4$x$0\mathrm{.}5=2$ Marks$)$

For an oscillator to start properly, the gain around the feedback loop must initially be

a$)$ One

b$)$ Greater than $1$

c$)$ Less than $1$

d$)$ Equal to attenuation of feedback circuit

In the Colpitts oscillator, the elements $x_1$ and $x_2$ are and $x_3$ is $a(n)$

a$)$ inductors, capacitor

b$)$ capacitors, inductor

c$)$ capacitors, resistor

d$)$ inductors, resistor

In the Wien bridge oscillator with $R1=R2=R$ and $C1=C2=C,$ a ratio of R $3$ to R $4$ will provide sufficient loop gain for the circuit to oscillate

a$)0$

b$)0\mathrm{.}5$

c$)1$

d$)2$

Oscillator

an AC input for giving an AC output.

a$)$ Doesn't need

b$)$ Need

c$)$ Doesn't need at lower frequencies

d$)$ Doesn't need at higher frequencies

Question II: Problem Solving

$(3$ Marks$)$

For the following current$-$series feedback circuit shown in figure $1,$ prove and calculate that:

a$)$ The voltage gain with feedback, $A_f$

b$)$ The input impedance with feedback

c$)$ The output impedance with feedback

Given: $A=-115,R_i=15k,$ and $R_o=35k$ for feedback $=0\mathrm{.}5$

Figure $1$: Lurrent$-$series reeaback circuit