B.S.T.J. Briefs: Stripline Downconverter with Subharmonic Pump

The process of frequency conversion and its applications are well known and have been extensively treated in the literature. 1-3 The conversion is usually performed by pumping a nonlinear resistive or reactive element embedded in a linear network and by extracting the sum or difference frequencies that are generated by the signal and the pump frequency. The purpose of this Brief is to describe a novel thin-film converter* which has the following properties: (i) The pump frequency required for efficient upconversion or downconversion is a submultiple of that needed in conventional frequency converters. (it) The circuit does not require a dc return path. (in) The separation of the signal and the pump frequency is readily obtained and the loss in the signal path is small. The new converter consists of two stripline filters and two Schottky barrier diodes, which are shunt mounted with opposite polarities in a strip transmission line. The conversion loss measured at a signal frequency of 3.5 GHz is 3.2 dB for a pump frequency of 1.7 GHz and 4,9 dB for a pump frequency of 0.85 GHz. The circuit looks attractive for use at millimeter-wave frequencies where stable pump sources with low FM noise are not readily available. * After the manuscript for this Brief was completed, it was learned t h a t M. Cohn, J. E. Degenford, and B. A. Newman at Westinghouse Electric Corp., Baltimore, Md., have begun independent work along similar lines. 1179