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What does current gain depend on?
According to “Gray & Meyer: Analysis and Design of Analog integrated circuits” transistor current gain Beta (in forward-active region) depend on operating conditions of the transistor.
When the collector current increases the gain of transistor?
As the temperature of a transistor increases, the collector current will increase because: Intrinsic semiconductor currrent between the collector and base increases with temperature. Its flow through the biasing resistors drives the base more positive, increasing forward bias on the base-emitter diode.
What is the current gain of common collector amplifier?
The current gain of a common-collector amplifier is equal to β plus 1. The voltage gain is approximately equal to 1 (in practice, just a little bit less). A Darlington pair is a pair of transistors “piggybacked” on one another so that the emitter of one feeds current to the base of the other in common-collector form.
How is the gain of a transistor calculated?
Transistor gain & Beta, β When undertaking many calculations the transistor current gain is given in terms of the Greek letter Beta; β. This is the forward current gain for the transistor when operated in a common emitter mode. Basic transistor current flows
What are the three conditions of a transistor?
A transistor in a circuit will be in one of three conditions. Cut off (no collector current), useful for switch operation. In the active region (some collector current, more than a few tenths of a volt above the emitter), useful for amplifier applications.
Is the current gain of a bipolar transistor constant?
It is normally expected that the value of current gain β for a bipolar transistor is constant, however there are some variations that occur in the value of β or h FE. β variations with collector current: The collector current level can cause a variation in the level of β or or h FE.
What are the rules of thumb for transistor action?
Some useful “rules of thumb” which help in understanding transistor action are (from Horowitz & Hill): A base emitter voltage VBEof about 0.6 v will “turn on” the base-emitter diode and that voltage changes very little, +/- 0.1v throughout the active range of the transistor which may change base current by a factor of 10 or more.