Error-Controlled High Power Linear Amplifiers at VHF

There are times when problems arise in device implementation that appear to be the product of the sheer perversity of the system designer. Worst of all, he can justify his need--as in the need to develop a solid-state 10-watt amplifier between 60 and 90 Mc, with low intermodulation distortion, time delay distortion, and gain ripple, with a high return loss, and with excellent time stability. Subsequently, a similar need was expressed over a band of 25 to 35 Mc. A format of amplifier design was devised meeting these requirements and subsequent constructions justified the design philosophy. While some of the techniques used are known, we believe that the nature of their use here emphasizes latent potentialities which had 651 652 THE BELL SYSTEM TECHNICAL JOURNAL, MAY-JUNE 1!)(J8 not been generally apparent. In particular, a "feed-forward" error compensation system is used which has parallels to McMillan's and Van Zelst's generalization of Black's error injection methods. 1-3 There is a very specific recognition here, however, of the physical role played by time, which dominates the form of the error network and which provides, among other advantages, a means of arbitrary error control of large time delay amplifiers which are intractable to feedback methods.* We shall describe further the use of "corporate" amplifier binary arrays using quadrature couplers and emitter-follower amplifier stages. The word "corporate" is intended to suggest the process of a corporate coordination of many sources to deliver their powers in some desired collective mode, in much the same fashion as in a corporate antenna.