Analog & Digital Electronics

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Analog & Digital ElectronicsCourse No: PH-218Lec-12: Frequency Response of BJT AmplifiersCourse Instructors: Dr. A. P. VAJPEYIDepartment of Physics, Indian Institute of Technology Guwahati, India1High frequency Response of CE Amplifier Athighfrequencies,internaltransistor junction capacitances docome into play, reducing an amplifier'sgain and introducing phase shift asthe signal frequency BJT, Cbeis the B-E junction capacitance, and Cbcis the B-C junction capacitance. (output to input capacitance)(output to input capacitance) At lower frequencies, the internal capacitances have a veryhighreactance because of their low capacitance value (usually only a few pf)and the low frequency value. Therefore, they look like opensand haveno effect on the transistor's performance. As the frequency goes up, the internal capacitive reactance's godown, and at some point they begin to have a significanteffect on the transistor's gain.

Analog & Digital Electronics Course No: PH-218 Lec-12: Frequency Response of BJT Amplifiers Course Instructors: Dr. A. P. VAJPEYI Department of Physics,

  Electronic, Analog, Digital, Analog amp digital electronics