Amplifier by their physical placement in the signal chain; a preamplifier may precede other signal processing stages, for example. The first practical electrical device which could amplify was the triode vacuum tube, invented in 1906 by Lee De Forest, which led to the first amplifiers around 1912. Today most amplifiers use transistors. The first practical device that could amplify was the triode vacuum tube, invented in 1906 by Lee De Forest, which led to the first amplifiers around 1912. Vacuum tubes were used in almost all amplifiers until the 1960s–1970s when the transistor, invented in 1947, replaced them. Today, most amplifiers
Xiaodong Wang (electrical engineer) Conference. Wang has many research interests, but chooses to focus on the areas of information theory, signal processing, and communications. Furthermore, he has influential published research in the areas of wireless communications, statistical signal processing, parallel and distributed computing, nanoelectronics, and quantum computing. In 2003 he published a book entitled "Wireless Communication Systems: Advanced Techniques for Signal Reception", published by Prentice Hall. Recently he is also working on the emerging field of genomics signal processing and information theoretic genomics. Xiaodong Wang (electrical engineer) Xiaodong Wang () is an information theorist and professor of Electrical Engineering at Columbia University. He earned