At the end of this unit you will be able to learn about theHybrid model (for low frequency)Calculation of h-parameters for different transistor configurationsHybrid pi-conductance in terms low frequency h-parametersHigh frequency hybrid -modelHigh frequency T-modelDifferent hybrid -conductancesFrequency response of a common emitterCommon emitter short-circuit current gainCommon emitter current gain obtained with hybrid pi-model

Cut-off frequencyGain bandwidth product (fT)High frequency current gain with resistive loadCalculation for the cut-off frequency

High frequency transistor differ from the low frequency transistor with reference to theoperating frequency. It means high frequency transistor operates at very high frequencynearly in the GHz range. The most obvious generality we can make about the fabrication ofhigh frequency transistors is that the physical size of device must be kept small. The basewidth must be narrow to reduce the transit time and the emitter and collector areas must besmall to reduce junction capacitance.

At the starting of this unit we will first discuss the hybrid model for transistor at lowfrequencies. At low frequencies it is assumed that the transistor responds instantly to thevariations in input signal (i.e., voltage or current). Finally, we will discuss high frequencyequivalent circuit for different possible configuration. It should be always kept in mind that,

Analog Electronics

Publisher : Laxmi Publications ISBN : 9788131802458Author : Balwinder SinghAnd Ashish Dixit

Type the URL : http://www.kopykitab.com/product/10032

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