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Figure 2: Adding an emitter resistor decreases gain, but increases linearity and stability. Common-emitter amplifiers give the amplifier an inverted output and can have a very high gain that may vary widely from one transistor to the next. The gain is a strong function of both temperature and bias current, and so the actual gain is somewhat ...
A Widlar current source is a modification of the basic two-transistor current mirror that incorporates an emitter degeneration resistor for only the output transistor, enabling the current source to generate low currents using only moderate resistor values. [1] [2] [3]
The transistor continuously monitors V diff and adjusts its emitter voltage to equal V in minus the mostly constant V BE (approximately one diode forward voltage drop) by passing the collector current through the emitter resistor R E. As a result, the output voltage follows the input voltage variations from V BE up to V +; hence the name ...
Resistor, R1, supplies the Zener current and the base current (I B) of NPN transistor (Q1). The constant Zener voltage is applied across the base of Q1 and emitter resistor, R2. Voltage across R 2 (V R2) is given by V Z − V BE, where V BE is the base-emitter drop of Q1. The emitter current of Q1 which is also the current through R2 is given by
See also an example of a mirror with emitter degeneration to increase mirror resistance. For the simple mirror shown in the diagram, typical values of will yield a current match of 1% or better. Figure 2: An n-channel MOSFET current mirror with a resistor to set the reference current I REF; V DD is positive voltage.
Figure 2: Basic N-channel JFET common-source circuit with source degeneration. In electronics, a common-source amplifier is one of three basic single-stage field-effect transistor (FET) amplifier topologies, typically used as a voltage or transconductance amplifier.
As a result, the common emitter resistor R E acts nearly as a current source. The output voltages at the collector load resistors R C1 and R C3 are shifted and buffered to the inverting and non-inverting outputs by the emitter followers T4 and T5 (shaded blue). The output emitter resistors R E4 and R E5 do not exist in all versions of ECL. In ...
The narrowing of the collector does not have a significant effect as the collector is much longer than the base. The emitter–base junction is unchanged because the emitter–base voltage is the same. Base-narrowing has two consequences that affect the current: There is a lesser chance for recombination within the "smaller" base region.