$7$

$($a$)$ Design a practical version of phase shift oscillators using BJT$,$ and Op$-$amp.

$($b$)$Investigate the oscillator frequency of designed circuits.

$($c$)$ To achieve better penetration and low attenuation of a telephone signal, design an RC phase shift oscillator to generate a carrier frequency of $15$ kHz that can carry audio signals.

$8$

$($a$)$ Construct a Wien bridge oscillator that serves as an appropriate power source for wirelessly charging of biomedical equipment.

$($b$)$ Investigate the oscillator frequency of designed circuits.

$($c$)$ Analyse the significance of ring oscillators in biomedical applications.

$9$

$($a$)$ Why instrumentation amplifiers are also called precision gain devices? Justify your interpretations of the application of this amplifier used in every medical device.

$($b$)$ Design an LED driver circuit with a supply of $20$ mA to drive the LED.

$($c$)$ Calculate the amplifier gain of the circuit of Fig. below for op$-$amp gain $A=100,000$ and resistances R$1=1\mathrm{.}8kV$ and $R2=200V.$

$10.$

$($a$)$ Explain ideal operational amplifier features.

$($b$)$ If an amplifier with gain of $-1000$ and feedback of $=-0\mathrm{.}1$ has a gain change of $20\%$ due to temperature, calculate the change in gain of the feedback amplifier.

$($c$)$ Determine the voltage gain, input, and output impedance with feedback for voltage$-$series feedback having $A=-100,Ri=10kV,$ and $Ro=20kV$ for feedback of

$($i$),=-0\mathrm{.}1,$ and

$($ii$)=-0\mathrm{.}5$