Vacuum Tube Op Amps
Development of Differential Amplifier Techniques
While amplifiers using both feedback and nonfeedback topologies were being refined in the late 1930s and throughout the 1940s, there were some very interesting developments within the realm of differential amplifiers.
Today’s op amps utilize differential topologies to a high degree, but the reader should understand that this wasn’t universally so back in the days of vacuum tube amplifiers. In fact, vacuum tube op amp topologies that fully utilized differential techniques never really became well established before the breed began dying off. Nevertheless, it is still a useful thing to examine some key differential amplifier publications up through about 1950, at ...