emitter degeneration การใช้

• E that introduces a significant negative feedback ( emitter degeneration ).
• Examples are imperfect voltage followers ( emitter degeneration ), whose input impedance is moderately increased.
• It is a Widlar mirror without an emitter degeneration resistor in the follower ( output ) transistor.
• Common-emitter stage with emitter degeneration that takes all the current, starving the other cutoff transistor.
• Figure 3 : Single-ended " npn " common-emitter amplifier with emitter degeneration.
• The Wilson current mirror achieves the high output impedance of equation ( 6 ) by negative feedback rather than by emitter degeneration as cascoded mirrors or sources with resistor degeneration do.
• The series negative feedback ( the emitter degeneration ) makes the transistors act as voltage stabilizers; it forces them to adjust their V BE voltages ( base currents ) to pass the quiescent current through their collector-emitter junctions.
• 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.
• If the emitter degeneration resistor is not present, then R _ { \ text { E } } = 0 \, \ Omega, and the expressions effectively simplify to the ones given by the rightmost column ( note that the voltage gain is an ideal value; the actual gain is somewhat unpredictable ).