# Questions tagged [common-collector]

A common collector amplifier (also known as an emitter follower) is one of three basic single-stage bipolar junction transistor (BJT) amplifier topologies, typically used as a voltage buffer.

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### Common Collector, Load Resistor Voltage Confusion

Using this link as reference: https://www.allaboutcircuits.com/textbook/semiconductors/chpt-4/common-collector-amplifier/ In this section of the book, the author was describing that the voltage of ...
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### Help me optimize common collector transistor amplifier for two quadrant LDO

I need some help with a circuit I can’t find much information online. Basic function should be a LDO which can source and sink current. To make it a bit more challenging there are some further ...
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### Common collector amplifier gives much less voltage than expected?

Common collector amplifier gives a good current gain and there is a link on internet, that makes the calculation for current amplification automatically. http://www.vk2zay.net/calculators/transistors/...
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### Why are only 3 of 6 single-transistor amplifier configurations useful?

Almost any analog design book or course I have ever seen starts by introducing the three basic single-transistor stages. For example, in a bipolar technology these are the common-emitter, common-base, ...
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### How to design BJT common collector amplifier?

I am working on a school project and I am struggling to design what is supposed to be an easy CC-amplifier. All other parts of the circuit are calculated and should work. The power amplifier is what's ...
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### Electrical characteristics on datasheet

What does this part of a datasheet mean? I always get confused when studying them... Is the user suppose to meet these conditions before getting the results stated on the sheet?
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### Does my common-collector current amplifier work correctly?

I have just built a 9V common-collector current amplifier to make my RF receiver more sensitive for 1-8Mhz. I used a voltage source in this circuit to make it clear how the circuit might work. The ...
2k views

### How to tell what configuration a transistor has in a complicated circuit

Apparently transistor Q15 in the following circuit is in common collector mode (well, actually it says it's an emitter follower but my understanding is that this is the same thing as common collector ...
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1 vote
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### Orcad: less than 2 connections on the emitter of the PN2222

I keep getting an error while simulating concerning the emitter node. Can anyone help?
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### DC Analysis of Common Collector Circuit with current source at emitter

For the circuit below I have to derive IB, R1 and R2 Since it is a DC-analysis, I turn the AC-sources off and make the capacitors open circuits. So the circuit becomes the following IB is straight ...
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### Common collector transistor

According to my understanding the common collector transistor should be like figure-1 but in book it is given as figure-2 and in it Vcc is given.Can anyone provide me proper explanation of this.
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### A good and valid example of Common Collector BJT

I am analyzing a common collector BJT as an amplifier using LTSpice. I have made the following circuit and I am not getting the exact characteristics which I should have got. Is there something wrong ...
2k views

### How to determine the input resistance of a bootstrapped emitter follower

I've used bootstrapping several times, either to boost the input impedance of an amplifier or to increase its gain. However most of the times I can see the beneficial effects of bootstrapping without ...
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