Question

A diode detector is used to detect an amplitude modulated wave of $60\%$ modulation by using a condenser of capacity $250pF$ in parallel with a load resistance $100$ kilo ohm. Find the maximum modulated frequency which could be detected by it.

Answer 1

Step 1. Given data:

Resistance $\left(R\right)=100\times {10}^3\Omega$

Capacitance $\left(C\right)=250\times {10}^{-12}F$

Modulation, $\mu =0.6$

Step 2. Formula used:

For a combination of resistance and capacitance,

Frequency can be given as: $f=\frac{1}{2\mathrm{\pi \mu RC}}$, where $R=$resistance, $C=$capacitence, $\mu =$modulation.

Step 3. Calculating frequency

Putting the given values in the above equation, we get

Frequency $\left(f\right)=\frac{1}{2\times 3.14\times 0.6\times 100\times {10}^3\times 250\times {10}^{-12}}=10.6167KHz$

Hence, the maximum modulated frequency that could be detected by it is $10.6167KHz$.