# What is Common emitter amplifier: Definition and 14 Discussions

In electronics, a common-emitter amplifier is one of three basic single-stage bipolar-junction-transistor (BJT) amplifier topologies, typically used as a voltage amplifier. It offers high current gain (typically 200), medium input resistance and a high output resistance. The output of an common emitter amplifier is 180 degrees out of phase to the input signal.In this circuit the base terminal of the transistor serves as the input, the collector is the output, and the emitter is common to both (for example, it may be tied to ground reference or a power supply rail), hence its name. The analogous FET circuit is the common-source amplifier, and the analogous tube circuit is the common-cathode amplifier.

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1. ### Engineering Alternative design for a CE-CC cascade amplifier

Here is a common CE-CC cascade amplifier- Here, the output of the emitter amplifier is directly connected to Q2, without any coupling capacitor or any voltage divider bias. This may harm the base-emitter junction of Q2 in case of unwanted output voltage from Q1 collector. But in that case, the...
2. ### Investigating the Effects of a Common Emitter Amplifier

Summary:: Using a common emitter amplifier to pump up the input voltage, and studying the effects henceforth. Here is a circuit with 0.6V pk-pk input voltage (v_in) for the CE amplifier, 1.17 kHz frequency- For this, without C5 and R9, the AC and DC gain was -10. I was supposed to increase...
3. ### Voltage Gain of a common-emitter amplifier

Hi, i have a problem with the voltage-gain of a common-emitter-amplifier. I have calculated the theoretical value of the gain given by ##G=\frac{\partial U_{a}}{\partial U_{e} } = -h_{FE} \frac{R_{c} }{R_{v} }## , which is between -13925 and -7311 for ##420\leq h_{FE} \leq 800## (given by the...
4. ### BJT transistor analysis: common emitter confusion

Recently I started studying semiconductors and analogue electronics. First I studied the diode and its I-V characteristics and analysis in DC circuits, as well as in AC circuits. Now I started with BJT transistors. I was explained that transistors act as electronic switches. My problem is not...
5. ### A question about common emitter amplifier

Homework Statement Hello my fellow PF mates! Today i received my electronic textbook from Russia. The book is great, however i can't explain myself one single equation, but i hope you will help me:-) The question is about the blocking capacitor in a common emitter amplifier. R1 and R2 are the...
6. ### Common emitter amplifier Electronics

Rb=40 ohms RL=100 ohms Vcc=15V I need help in figuring this problem out, I understand if anyone here doesn't want to give me the answer but I would appreciate if someone would give me a formula in which I could solve the problem myself.
7. ### Simple Common Emitter Amplifier

Hey guys. I'm jumping into the world of electronics out of boredom and curiosity and am trying to wrap my mind around a few things. I'm on the topic of Transistors presently and have spend many hours learning about it's different modes of operation. I'm a bit confused about the Forward Active...
8. ### BJT: Common Emitter Amplifier Gain

So I have a question regarding the gain of common emitter amplifier. Referring to the attached diagram, the voltage gain of the circuit is -RC/RE. However, I don't understand how Vbb can be removed when completing the analysis. I've done the KCL analysis by hand and keep getting a gain function...
9. ### Common Emitter Amplifier Design

Homework Statement I have to design a Common Emitter Amplifier using a 2N2222 NPN transistor and an 18V DC supply. The specifications are as follows: Should be stable for variations in forward current gain, β. The input signal to the amplifier is a 0.2 Vp sinusoidal signal, at a frequency of...
10. ### Common Emitter Amplifier Analysis

This is my analysis of common emitter amplifier. Ic = βIb Ic ≈ Ie (because Ib is very small) => Ie = βIb Vcc = IcRc + Vce + IeRe Vcc = IeRc + Vce + IeRe Vce = Vcc - βIb(Rc + Re) Vb = IbRb + Vbe + IeRe Vb = Ib(Rb + βRe) + Vbe Gain = Vce/Vb Gain = (Vcc - βIb(Rc + Re))/(Ib(Rb + βRe)...
11. ### Basics of Common Emitter amplifier.

Hello experts! I have some question related to this configuration of BJT. 1)Why we use capacitor at the base of the circuit?(Answer: To decouple DC so that our signal that is reaching to base of the transistor is not to be DC shifted that's why it is called "Coupling capacitor". If it is...
12. ### Common Emitter Amplifier

Can someone please explain to me with what reasoning RL and RC are taken to be in parallel when calculating Vo for any decrease/increase in IC (DC) due to isig (ac) Thank you
13. ### Capacitors in Common Emitter Amplifier Circuit ?

Capacitors in "Common Emitter Amplifier" Circuit ? Should i use Capacitors in "Common Emitter Amplifier" ( CEA ) Circuit ? As i saw many CEA circuits designed without any capacitors there ! And also hear that it's better to use two capacitors, one after the Voltage Source ( that feeds the...
14. ### Engineering Common emitter amplifier circuit using feedback biasing

i don't have the basic of analog, but i tried to look for in the books. unfortunately, the books are using voltage divider biasing instead of feedback biasing. i have a circuit like this: http://www.mrnerdy.com/forum_img/BJTampfeedbackbiase.jpg would anyone tell me the flow of the current in...