High-power varactor frequency-doubler chains

The joint authors of this comprehensive paper are all British, and have been employed on Standard Communication Laboratories on variable frequency multipliers for periods ranging from 10 to 25 years. The paper deals with varactor frequency doubters operating in the forward-bias region, which increases the power handling capacity of the varactor. The varactors used were all silicon types from several manufacturers. It is impossible to deal adequately in an abstract with the many points covered, and the paper must be studied in detail. The authors discuss the characteristics of the varactor diode, and deal with various coupling networks and chains of frequency doubters, and then pass on to design of doubter stages. Circuit diagrams and curves are given, with a typical circuit comprising 4 cascaded doubter stages. The latter part of the paper deals with circuit design, and the use of the Smith chart to select appropriate component values. A design example is worked out and experimental results given. The authors have succeeded in presenting information on the design of such chains, applicable over a wide range of frequencies. The paper is a valuable contribution to the subject, and should assist in the economical construction of high-speed multiplier chains.