Abstract: Circuits and methods of dynamic modulation are disclosed. A dynamic modulator is used to reduce measurable conducted and/or radiated electromagnetic interference (EMI). The dynamic modulator is configured to generate either a set of optimal frequency modulation depths or discrete frequencies or both, and dynamically selects them to use over a series of programmable time durations (dwell time). Together with the utilization of Peak, Average or Quasi-Peak (QP) method of measurement, the dynamic modulator can reduce the spectral amplitude of EMI components, in particular the lower harmonics, to effectively pass regulatory requirements. In alternative embodiments, the dynamic modulator is used in a closed loop system to continuously adjust the frequency and the duty cycle of a PWM signal to reduce conducted and/or radiated EMI.

Abstract: This invention discloses a novel apparatus of fully depleted emitter so that the built-in potential between emitter and the base becomes lower and the charge storage between the emitter and base becomes small. This concept also applies to the diodes or rectifiers. With depleted junction, this results in very fast switching of the diodes and transistors. Another novel structure utilizes the strip base structure to achieve lower on resistance of the bipolar transistor. The emitter region of the strip base can be a normal emitter or depleted emitter.

Abstract: A fast recovery rectifier structure with the combination of Schottky structure to relieve the minority carriers during the forward bias condition for the further reduction of the reverse recovery time during switching in addition to the lifetime killer such as Pt, Au, and/or irradiation. This fast recovery rectifier uses unpolished substrates and thick impurity diffusion for low cost production. A reduced p-n junction structure with a heavily doped film is provided to terminate and shorten the p-n junction space charge region. This reduced p-n junction with less total charge in the p-n junction to further improve the reverse recovery time. This reduced p-n junction can be used alone, with the traditional lifetime killer method, with the Schottky structure and/or with the epitaxial substrate.

Abstract: This invention disclosed a novel method of fully depleted emitter so that the built-in potential between emitter and the base becomes lower and the charge storage between the emitter and base becomes small. This concept also applies to the diodes or rectifiers. With depleted junction, this result in very fast switching of the diodes and transistors. Another novel structure utilizes the strip base structure to achieve lower on resistance of the bipolar transistor. The emitter region of the strip base can be a normal emitter or depleted emitter.