When people entered the electrical age, they began to explore the amplification of electrical signals. In 1880, Edison added a third electrode in addition to the two electrodes of the ordinary bulb in the experiment of bulb research, and added some foils. He was surprised to find that the foil was positive when the third pole was positive. No reaction, but the foil has a churning motion when the battery is negative. His inadvertent discovery is actually the prototype of a vacuum electronic diode.
In 1904, John Fleming invented the vacuum diode based on the principle of the Edison effect, and in 1907 Lee DeFrest invented the first vacuum transistor, and the world entered the electronic age. After that, in 1947, semiconductor technology-based bipolar transistors were invented by Bell Labs's John Bardington, Walter Braden, and William Shockley. Electronic technology entered a golden age of leaps and bounds. The more you enter into people's lives.
The essence of an analog amplifier is to use a signal of smaller amplitude or power to control a signal of greater amplitude or power. For example, electric guitars, everyone knows that many electric guitars do not have a resonance chamber. The actual sound produced by hand plucking strings is actually very small, but the electronic amplification device used can generate the sound that the entire stadium is boiling. A magnet is placed under the strings of the electric guitar. When the metal strings vibrate, the magnetic induction lines of the magnets are cut to generate a weak voltage, and these voltages are used as inputs of the amplifier to control the electric signals of the higher power to drive the speakers. Produces a loud sound. The power amplifiers that originally used tubes have at least a suitcase size, and the semiconductor technology power amplifiers currently used in cell phones are only a few square millimeters.
Although more and more signal processing in life, storage uses digital technology, but the simulation technology is still used in our observation of the world's entrance hospital biochemical equipment, optical sensors in the camera, accelerometers and gyroscopes in mobile phones, etc. They are all state of the art analog technology.
In the era of digital survival, we still cannot do without traditional analog technology, because the real world is always "simulated."