- #1

RockyRoad

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## Homework Statement

Plot |z| vs. f(Hz) of the circuit. R=100, C=600 pf = 6E-12 F, L=10E-6 H . All elements of the circuit are in parallel. Also identify the resonant frequency.

## Homework Equations

ZR=R

ZL=jwL

ZC=1/(jwC)=-j/(wC)

w=2(pi)f

w0=1/sqrt(LC)

f0=1/(2(pi)sqrt(LC))

G=1/R

## The Attempt at a Solution

Z1=ZR

Z2=ZL

Z3=ZC

Zeq= 1/((1/R)+1/(jwL)+jwc)

Switching to admittance and skipping a few steps, it can be found that

Y=G + j * 2 * pi * f * C * (1 - (f0 / f) ^ 2)

Z=R + 1 / (j * 2 * pi * f * C * (1-(f0 / f) ^ 2))

Z=100 + 1/(j * 2 * pi * f * 600E-12 *(1 - (2054681.48 / f) ^ 2)

To plot, i used a few lines in matlab:

f=linspace(0,4000000,100000);

x=1i.*2.*pi.*(600.^(-12));

z=100+(1./(x.*f.*(1-((2054681.48./f).^2))));

plot=semilogx(z);

The plot shows me a vertical line at f=100

My professor told us that the graph should be bell shaped, and i have no idea where i've gone wrong. Anyone see a mistake?