The answer scrawled on a blank page in a daily newspaper, was conceived whilst aboard a ferry.

IEEE. He held many patents the most famous of which was US Patent 2102671 "Wave Translation System" which was issued to Bell Laboratories in 1937 covering the negative feedback amplifier. By sacrificing gain it also has an additional effect of increasing the bandwidth of the amplifier.

It is the invention of negative feedback which makes highly linear amplifiers possible. Once the stability problem is solved the negative feedback amplifier is extremely useful in the field of electronics. However a negative feedback amplifier can be unstable such that it may oscillate.