This lecture covers the fundamentals of filters, focusing on the LP-to-HP transformation. It explains how the LP-to-HP transformation is obtained by frequency inversion, detailing the frequency transformation equations. The impedance transformation process for capacitors and inductors is also discussed, along with examples of LP-to-BP transformations. The lecture delves into the design considerations for LP-to-BP transformations, emphasizing the importance of equalizing attenuation in stopbands and adjusting cutoff frequencies. Additionally, it explores circuit transformations and impedance changes in passive LC filters. The session concludes with a Q&A segment on exam preparation, addressing various concepts related to active filters and impedance transformations.