Second-order distortion in CATV push-pull amplifiers

There are several techniques available for the transportation and distribution of multichannel television signals or, for that matter, multicarriers of any kind, involving the use of repeater amplifiers. One such technique uses push-pull amplifier equipment and, avoiding the pros and cons of the various methods, this paper briefly discusses some of the advantages of push-pull amplifiers and treats in detail the second-order distortion in such amplifiers. A mathematical model of a push-pull amplifier is designed and various manipulations are performed on the model in order to determine its behavior in relationship to a design goal of -66 dB for second-order beats. Practical amplifiers are built and measurements are performed, with the results confirming the theory.