Harold Stephen Black

Harold Stephen Black was an American electrical engineer, who revolutionized the field of applied electronics by inventing the negative feedback amplifier in 1927. To some, his invention is considered the most important breakthrough of the twentieth century in the field of electronics, since it has a wide area of application. This is because all electronic devices are inherently nonlinear, but they can be made substantially linear with the application of negative feedback. Negative feedback works by sacrificing gain for higher linearity . By sacrificing gain, it also has an additional effect of increasing the bandwidth of the amplifier. However, a negative feedback amplifier can be unstable such that it may oscillate. Once the stability problem is solved, the negative feedback amplifier is extremely useful in the field of electronics. Black published a famous paper, Stabilized feedback amplifiers, in 1934.

He was born in Leominster, Massachusetts in 1898. He went to Worcester Polytechnic Institute for his first degree. Subsequently, he received a B.S.S. in Electrical Engineering from WPI in 1921 and then joined Western Electric, which was the manufacturing arm of ATampT. He joined Bell Labs , where he was a member of technical staff until his retirement .

Source: Wikipedia