we know that there is an emitter resistance Re...
the resistance is grounded..
so technically speaking the emitter lead is connected to some positive value of potential(+ve end of resistor)
but in CE,emitter is supposed to be grounded.is't it??
2007-03-21 04:50:12 · 4 answers · asked by sriraam h 2 in Science & Mathematics ➔ Engineering
The configuration that you are describing is actually called a common CE with a resistance in the emitter, not the standard CE configuration.It usually looks just like the CE configuration, except without the bypass capacitor that goes between the emitter and ground. It is a basic form of feedback. This configuration is used to tailor the circuit to your overall design requirements. There are certain trade offs with this circuit.
The bad:
1. gain will be lower
2. transconductance will be lower
The advantages of this circuit:
1. gain becomes much less dependent on Beta
2. the input resistance is increased by a factor of (beta + 1)
3. a larger input signal can be applied without risking distortion
4. the high frequency response is significantly improved
2007-03-21 05:59:35 · answer #1 · answered by dylan k 3 · 0⤊ 0⤋
As long as the input is on the base and the output is on the collector, it is a CE (Common-Emitter) amplifier. The emitter can be used for biasing and negative feedback. The emitter resistor causes negative feedback by raising the emitter voltage as more current flows, which decreases the base-emitter voltage. Negative feedback helps the CE amplifier operate over a wider range of conditions and reduces the gain. With the emitter resistor, the bias current and gain of the CE will be less dependent on beta, supply voltage, and other parameters.
2007-03-21 12:23:15 · answer #2 · answered by Gigabit 1 · 0⤊ 0⤋
In a CE amplifier, there are two ways to treat the emitter connection. You can physically ground it OR you can leave in the emitter resistor for biasing and bypass it with a capacitor. For a sufficiently large bypass cap, the emitter looks like it's shorted for an ac signal
2007-03-21 11:55:59 · answer #3 · answered by Gene 7 · 0⤊ 0⤋
Not necessarily. Common-emitter simply characterizes the amplifier as having an input at the base, and output at the collector. If the input was at the base, and output was at the emitter, then we'd have a common collector amplifier. If input was at the emitter and output at the collector, you'd have a common-base amplifier. Common-emitter, collector or base configuration doesn't dictate what biasing or resistance is used.
2007-03-21 12:11:54 · answer #4 · answered by joshnya68 4 · 0⤊ 0⤋