Question

Part 5 The frequency response of RLC circuits :

Design a passive filter: Band Pass, ISM Band 433.050 MHz to 434.790 MHz . Prepare a report to describe your design. Your results should include the following :
i. Simulation of the designed filters by using any simulation software.

ii. Attach a 1 kΩ resistor as a load to the initial design of your filter. Explain how the transfer function change. Does the type of filter
change? Does the cut-off frequency change?

iii. Is it possible to build a second order filter with only resistors and capacitors? Justify your answers.

Marks will be given based on the literary, originality, design procedures, results, discussion, conclusion, presentation, references and writing skills.

Answer 1

(ii)

Adding 1 kohm load resistor, the output of the circuit changes a little bit due to additional loading effect which can be clearly seen the in the next figure

No, the cut off frequency will not change significantly.

(iii)

Yes, second order filter can be built by resistor and capacitor. The order of the filter is determined by the number of charging elements present in the circuit. If there are two capacitor present directly between the input and output of a circuit then it can be called as a second order filter. A typical second order filter with cutoff frequency f_C is shown below in the figure: