Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [common-emitter]

A common emitter is one of three basic bipolar junction transistor (BJT) amplifier topologies. It is notorious for a high power gain. It is the only one-stage BJT amplifier topology that permits gain both in voltage and current.

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What is the purpose of the emitter resistor in a common emitter amplifier?

I'm struggling to understand the purpose of the resistor circled in red, I know it has something to do with DC biasing and the feedback on the circuit (as the capacitor will cause AC bypass). But I'm struggling to understand the exact circumstance…
kiwithegreenmileran
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Common Emitter not amplifying

I am trying to make a 27 MHz carrier wave transmitter from a crystal oscillator and a secondary amplifier. This is the complete circuit: simulate this circuit – Schematic created using CircuitLab The first part, left of C6 is a colpitts crystal…
Golaž
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Is it misleading to say a common emitter amplifier is “out-of-phase”?

I now understand that a common emitter amplifier produces an inverted amplification. I am asking this question because for a bit, I was hung up around the frequency with which I heard it explained as having an output that is “180 degrees…
shafe
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Irregular common emitter amplifier design

Would anyone know of any merits (or demerits) to the common emitter amplifier represented in Figure 1 in comparison to one of a regular pattern (Figure 2)? Thanks. (The 'DS548' transistor in Figure 1 is just a BC548.) (The diode in Figure 1 is just…
kene02
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How to calculate capacitor values in a Common Emitter amplifier?

Ok so I am designing a Common Emitter amplifier using a BJT and this has been driving me crazy for the past four days. Yes, this is for an assignment and I am not asking to have my homework done; my intent is to fully understand the circuit and how…
Kevin KZ
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My RF amplifier circuit works in LTSpice. Will it work in reality, too?

I am working now for a while with bias calculations. I have found a good turorial to calculate it by my own and I have seen that there are already calculators on internet, which made my life much easier than i supposed to manage. I have now a…
lastime
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Is it possible to reduce distortion in a common emitter amplifier?

I am designing a common emitter amplifier for educational purposes. I work in a different engineering field so please bear with me. The gain of the circuit is around 26 (enough for my purpose), but it has a distortion (measured in LTspice) of 2.9%…
Rojj
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Transistor amplifier design

I need to design a common emitter amplifier for my next electronics laboratory. Specifications are the following: 1 mA of collector current Load resistance of 1k ohms Voltage gain of 10 For 1mA, $$ \beta = 185 $$ according to the datasheet. So to…
Santiago López
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Cascading common emitter and common collector

I am trying to design an amplifier for a 1 W 8 ohm speaker for educational purposes. The idea is to start from a common emitter amplifier to amplify voltage and then add a common collector (emitter follower) amplifier to amplify power and deal with…
Rojj
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Designing 2-stage BJT CE class-A voltage pre-amplifier with specified goals and without global NFB

BJT CE Class-A Voltage Pre-Amplifier Suppose a design requirement limits the selection choices to the following class-A BJT common emitter stage topologies. No global NFB is permitted. Only local NFB via the emitter leg with passive components as…
jonk
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Output voltage for operational amplifier goes to supply rails

I've been trying to understand the innards of an op amp and I'm having a hard time understanding why the output looked clipped. Below is the schematic I got from Hackaday. I've simulated this in LTSpice. Here is the input(SINE source, green line)…
hellowurf
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How to derive the precise gain of an NPN common emitter amplifier without emitter degeneration?

As a self imposed exercise, I tried to derive the complete expression of gain in a common emitter amplifier without emitter degeneration. I mean by "complete" that it also takes into account the distortion associated with it. Here is my…
Sachiko.Shinozaki
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Adding negative feedback to a common-emitter transistor amplifier

I am trying to learn how to implement negative feedback to a common-emitter configuration.The goal is to reduce distortion by sacrificing some of the gain. simulate this circuit – Schematic created using CircuitLab This is how the complete circuit…
Daniel Tork
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How to correctly bias an NPN transistor without allowing base voltage to be too high

simulate this circuit – Schematic created using CircuitLab I am trying to correctly bias a BC337 NPN whose collector is connected to a 9V source. I wish to use it as a switch in response to a separate signal (which is either 0V or 9V) applied to…
RickyBoy
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Active load role on this circuit and possible uses

simulate this circuit – Schematic created using CircuitLab I came with this circuit to know how an active load can improve it, I still can't finish to understand the role of active loads. The far I know is that below, Q5-Q6-R2 form a current source…
tac
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