Hello! Thank you so much for taking the time to leave such a thoughtful review. With your physics background, you must have a solid theoretical foundation, and I'm truly proud as an instructor to hear that my 'intuitive approach' helped you understand OP-AMP operating principles and practical applications. While analog circuit design can feel like it has a high barrier to entry, I'm confident that with your perspective of seeing through to the 'physical essence' as you do now, you'll become an excellent engineer. If you encounter any difficulties while studying, please feel free to post questions on the Q&A board anytime. I sincerely support your career path! Fighting!