# Matched LPF (without reflections)

Hey,
I analyzed the circuit (matched LPF without reflections) hereby attached and produced a simulation of its impedance(freq.). I am now asked to explain why it is important to use a filter with such input impedance at high frequencies. If the filter's impedance at high frequencies were, say, 50ohms I could probably answer - "impedance matching! Thus benefiting from maximum power transfer etc.", but since at high frequencies the impedance approaches 0 I am not quite sure what the answer in this case should be. I'd appreciate some insight, please.

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berkeman
Mentor
Hey,
I analyzed the circuit (matched LPF without reflections) hereby attached and produced a simulation of its impedance(freq.). I am now asked to explain why it is important to use a filter with such input impedance at high frequencies. If the filter's impedance at high frequencies were, say, 50ohms I could probably answer - "impedance matching! Thus benefiting from maximum power transfer etc.", but since at high frequencies the impedance approaches 0 I am not quite sure what the answer in this case should be. I'd appreciate some insight, please.

What is the purpose of the input capacitor? It looks misplaced. Does that AC voltage source to the left have a built-in output resistance/impedance?

Baluncore