An Analysis of Finite Rise and Fall Time Current Excitation of Trapatt Diodes

摘要

It is shown that the square wave current excitation requires negative impedance terminations above the 5th harmonic. Since the harmonic amplitudes in a square wave decrease only as 1/n, harmonics as high as the 9th and 11th must be properly terminated to make the analysis realistic and to prevent premature avalanche. We have analyzed the TRAPATT operation using the same physical approximations for plasma formation and recovery as used in the previous square wave analyses. However, we have assumed a trapezoidal current waveform which contains primarily first and third harmonics with negligibly small higher harmonics. In this analysis the avalanche zone transit and portions of the plasma extraction process occur while the current is changing. The resulting device voltage is calculated as a continuous analytical function of time except during the plasma formation interval and the final saturated velocity phase of the plasma extraction interval, where an interpolated voltage waveform is obtained. Fourier analysis of the voltage waveform provides the device efficiency as well as the necessary circuit termination at the 1st and 3rd harmonics. (Author)