A Theory of Multiple Modes in Avalanche Diodes

Abstract

This report develops a multidimensional, dynamic analysis of solid state avalanche diodes. Well-established electromagnetic concepts are applied to a widely used model of the diode and reveal a discrete spectrum of new small-signal modes. The approach used enlarges the conventional perspective and has permitted the discovery that at least one of these new modes appears to possess a high power capability (associated with its two-terminal negative resistance) which has been partially realized experimentally. The lowest-order mode contains all the results of prior quasi-static theories on the normal IMPATT mode, plus additional information which is used to delineate the range of validity of the quasi-static results. Formal discrepancies are uncovered between the usual quasistatic, one-dimensional result for diode impedance used in solid state studies and the dynamic multidimensional result for the normal IMPATT mode developed from microwave circuit theory. However, these discrepancies are numerically quite small except in certain narrow frequency bands.