Meanwhile exists essentially simple sharp increase of efficiency of diode. It consists in replacement of modulation of electrons on speed with modulation on current on an entrance to a diode interval.
This energy is negative, i.e. there is a transformation of kinetic energy of electrons in energy of a high-frequency field. In the corresponding ranges of frequencies the active resistance of the diode negatively.
Therefore the main conclusions about properties of a field with the late issue made above, and to avalanche flying diode. It concerns, in particular, reasons about influence of a volume charge of carriers on oscillatory properties of the generator on the avalanche and flying diode. Getting to flying space, the main carriers partially neutralize a spatial charge of ions of impurity and reduce a field in a multiplication layer. This effect facilitates generator conditions at frequencies above and interferes with emergence of parasitic fluctuations at lower frequencies, where an active of the diode positively.
In the previous reasonings we proceeded from purely kinematic model, neglecting influence of an charge on group of electrons in a diode. Meanwhile this influence in many options of diode generators is many. Especially a a role of a volume charge in diodes with field issue in which an electronic volume charge, intensity of electric field at the cathode, influences issue current. In essence the volume charge creates a peculiar mechanism of internal negative feedback in the diode. If issue current instantly follows a field, this negative feedback is reduced only to restriction of the average current proceeding via the diode. However, if issue is inertial, situation changes.
However as the group of electrons and selection of high-frequency power occur in the same flying space at absence in this of the slowed-down electromagnetic waves, the of such interaction is small also an absolute of active resistance of the diode much less than a size of its jet (capacitor) resistance. Therefore for creation of the oscillator in the microwave oven range it is necessary to connect to the diode an external contour with good quality and to remove very big density of current from the cathode. In this regard realization of similar generators met considerable difficulties and they did not find practical application.
The imperative need of miniaturization of an of the microwave oven, increase of its profitability and reliability caused rapid growth of working frequencies of devices. Along with great success in a of transistors it was promoted by the opening of the new physical phenomena in semiconductors which made development of the devices adequate to the microwave oven to a.
The subsequent experiments showed that the similar phenomena (generation of the microwave oven of fluctuations) can and on diodes of other structure: diffusive on base n-Germany, floatable germanic diodes with a r-p transition, diffusive and floatable diodes etc.
This lack is met considerably by the new semiconductor microwave oven the device — the avalanche and flying diode (LP which is a basis of the whole class microwave oven of devices; generators, amplifiers and converters of frequency.
Diodes with dynamic negative the are known in vacuum electronics 60 years. L. Levellin experimentally showed possibility of creation on the basis of such diode of the microwave oven generator. The scheme of the similar generator includes the diode limited to two electrodes — the cathode and the anode to which constant U0 and U ~ potential differences, and an external contour is attached.