Subject and UNIT: Electronic Devices and Circuits: Unit II: Amplifiers
Anna University Important Solved Problems
Subject and UNIT: Electronic Devices and Circuits: Unit II: Amplifiers
Need for Multistage Amplifiers: 1. When amplification of single stage amplifier is not sufficient. 2. When input or output impedance is not of correct magnitude for the intended application. 3. To increase the overall gain.
Gain and Frequency Response of BJT Amplifier, Gain and Frequency Response of FET Amplifier
Subject and UNIT: Electronic Devices and Circuits: Unit II: Amplifiers
All the coupling and bypass capacitors have been assumed to be short circuited and wiring capacitance is ignored.
Subject and UNIT: Electronic Devices and Circuits: Unit II: Amplifiers
The input signal is fed at the gate similar to the common source amplifier. The signal output is taken at the source terminal.
Steps Involved in Small-Signal Analysis of MOSFET,
Subject and UNIT: Electronic Devices and Circuits: Unit II: Amplifiers
Small signal parameters are controlled by the Q-point. For the same operating point, MOSFET has lower transconductance and an output resistance that is similar to the BJT.
Comparison of CE CB and CC Amplifiers
Subject and UNIT: Electronic Devices and Circuits: Unit II: Amplifiers
The collector terminal is common between the input and output terminals. The input is applied at the base and the output is taken across the emitter terminal.
Construction, Operation, Characteristics, Application
Subject and UNIT: Electronic Devices and Circuits: Unit II: Amplifiers
The base terminal is common between the input and output circuit. The input is applied to emitter terminal and output is taken from the collector terminal.
h-parameter model, Characteristics of CE Amplifier, Applications
Subject and UNIT: Electronic Devices and Circuits: Unit II: Amplifiers
Characteristics of CE Amplifier: i. Good voltage gain ii. Phase inversion i.e., output voltage is 180° out of phase with input iii. Good current gain and power gain iv. High input and output impedance
Transistor as a Two Port Device, Small Signal Analysis, Analysis of CE Amplifier
Subject and UNIT: Electronic Devices and Circuits: Unit II: Amplifiers
Any two parameters are considered to be independent variables and the other two parameters are expressed in terms of the independent variables.
Subject and UNIT: Electronic Devices and Circuits: Unit II: Amplifiers
The self bias technique given for JFET cannot be used for establishing an operating point for the enhancement MOSFET because of the voltage drop across RS is in a direction to reverse bias the gate and it actually needs forward gate bias.
Subject and UNIT: Electronic Devices and Circuits: Unit II: Amplifiers
For the proper functioning of a linear FET amplifier, it is necessary to maintain the operating point Q stable in the central portion of the pinch off region. The Q point should be independent of device parameter variations and ambient temperature changes.
Transistor Biasing
Subject and UNIT: Electronic Devices and Circuits: Unit II: Amplifiers
A common emitter amplifier using fixed bias circuit. The dc analysis of the circuit yields the following equation.