Topic: Analog Circuits / Electromagnetics
A source with internal resistance $Rs=50~\Omega$ is to be matched to a load $RL=200~\Omega$ using a lossless LC network at a frequency of 10 MHz. Which of the following configurations will provide proper impedance matching and high-pass filtering?
- A. A series inductor followed by a parallel capacitor
- B. A parallel inductor followed by a series capacitor
- C. A series capacitor followed by a parallel inductor
- D. A parallel capacitor followed by a series inductor
Answer: C. A series capacitor followed by a parallel inductor
Explanation: To achieve a high-pass filter response, the series element must block low frequencies (so it must be a capacitor) and the shunt (parallel) element must short low frequencies to ground (so it must be an inductor). Since $R_L > R_S$ (200 $\Omega$ > 50 $\Omega$), the standard L-section matching network places the shunt element in parallel with the higher resistance (the load). Therefore, the correct configuration from source to load is a series capacitor followed by a parallel inductor.