One of the prerequisites for the development of telecommunication services is the
understanding of the propagation of the waves, either acoustic, electromagnetic,
radio or light waves, which are used for the transmission of information.
In this work, we shall limit ourselves to the study of radio waves: this term
apply to the electromagnetic waves used in radio communications. Their
frequency spectrum is very broad, and is divided into the following frequency
bands : ELF waves (f < 3 kHz), VLF (3-30 kHz), LF waves (30-300 kHz), MF
waves (300-3000 kHz), HF (3-30 MHz), VHF waves (30-300 MHz), UHF waves
(300-3000 MHz), SHF waves (3-30 GHz), EHF waves (30-300 GHz) and sub-
EHF waves (300-3000 GHz).
標(biāo)簽：
Propagation
Radio
Wave
上傳時(shí)間：
2020-06-01
上傳用戶：shancjb
le flows through MOS channel while Ih flows across PNP transistor Ih= a/(1-a) le, IE-le+lh=1/(1-a)' le Since IGBT has a long base PNP, a is mainly determined by ar si0 2ar= 1/cosh(1/La), La: ambipolar diff length a-0.5 (typical value)p MOSFET channel current (saturation), le=U"Cox"W(2"Lch)"(Vc-Vth)le Thus, saturated collector current Ic, sat=1/(1-a)"le=-1/(1-a)"UCox"W/(2Lch)"(Vo-Vth)2Also, transconductance gm, gm= 1/(1-a)"u' Cox W/Lch*(Vo-Vth)Turn-On1. Inversion layer is formed when Vge>Vth2. apply positive collector bias, +Vce3. Electrons flow from N+ emitter to N-drift layer providing the base current for the PNP transistor4. Since J1 is forward blased, hole carriers are injected from the collector (acts as an emitter).5. Injected hole carriers exceed the doping level of N-drift region (conductivity modulation). Turn-Off1. Remove gate bias (discharge gate)2. Cut off electron current (base current, le, of pnp transistor)
標(biāo)簽：
igbt
上傳時(shí)間：
2022-06-20
上傳用戶：wangshoupeng199
