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Configuraciones básicas del amplificador BJT

There Are Plenty of texts around on basic electronics, so this is a very brief look at the basic three Ways in Which a bipolar junction transistor (BJT) Can Be used.
There are plenty of articles about basic electronics, so this is a very brief three basic ways in which a bipolar junction transistor (BJT) can be used. Each

In case, one terminal is common to Both the input and output signal.
In each case, a terminal is common to the input and output.

All the circuits Shown Here Are Without bias circuits and power supplies for clarity.

All circuits shown here are without bias circuits and power supplies for clarity.

Common Emitter Configuration

common emitter configuration

Here the emitter terminal is common to Both the input and output signal. Here, the emitter terminal is common to both the input and output.
The arrangement is the Same for a PNP transistor. The layout is the same for a PNP transistor.

Used in this way the transistor has the Advantages of a medium input impedance, medium output impedance, high voltage gain and high current gain. Used this way the transistor has the advantages of a medium input impedance, output impedance media, high voltage gain and high current gain. Common Base Configuration Common Base Configuration

Here the base is the common terminal. Here the base is the common terminal.
Used frequently for RF Applications, this stage has the Following properties.
is often used for RF applications, this stage has the following properties.
Low input impedance, high output impedance, unity (or less) current gain and high voltage gain. Low input impedance, high output impedance, unity (or less) and gain increasing high voltage.
Common Collector Configuration Settings common collector

This last configuration también more Commonly Known As the emitter follower.
This configuration is more commonly known as the emitter follower. This Because the input signal is Applied at the base is "follow" quite Closely at the emitter with a voltage gain close to unity. This is due to the input signal is applied to the base is "followed" very closely in the transmitter with a voltage gain close to unity. The properties Are to high input impedance, a very low output impedance, a unity (or less) voltage gain and a high current gain. The properties are a high input impedance, a very low output impedance, a unit (or less) voltage gain and high current gain. This circuit también Used extensively as a "buffer" converting Impedances or for feeding or driving long cables or low impedance loads. This circuit is also widely used as a "buffer" converting impedances or for feeding or driving long cables or low impedance loads.

Transistor Configuration Comparison Chart
transistor Comparison Chart Settings

(see Sedra & , Smith and "Detailed Analysis" below) (See Sedra & Smith and "detailed analysis" below)

AMPLIFIER
TYPE AMPLIFIER TYPE


COMMON EMITTER COMMON EMITTER HIGH HIGH or Grounded Emitter Amplifier (current circuit configuration

COMMON BASE BASE COMMON
COMMON EMITTER EMITTER COMMON	(Emitter Resistor) (strength of the issuer)	COMMON COLLECTOR common collector	(Emitter Follower) (Follower issuer) INPUT / OUTPUT PHASE RELATIONSHIP INPUT / OUTPUT PHASE RELATIONSHIP	0° 0 ° 180°
180 ° 180°	180 ° 0°	0 ° VOLTAGE GAIN	Voltage Gain
MEDIUM MEDIUM	MEDIUM MEDIUM	LOW LOW	CURRENT GAIN Current Gain	LOW LOW to a
MEDIUM HALF	MEDIUM HALF b b	HIGH HIGH	POWER GAIN POWER GAIN	LOW BAJA HIGH
ALTO HIGH	ALTO MEDIUM	MIDDLE INPUT Resistance	input resistance LOW	low
MEDIUM HALF	MEDIUM MEDIUM	HIGH HIGH	OUTPUT RESISTANCE output resistance	HIGH HIGH
MEDIUM HALF	MEDIUM HALF	LOW low	Detailed Analysis Detailed analysis Common	) common or grounded emitter amplifier ( real circuit configuration )

CE Amplifier Small-Signal Equivalent Circuit
EC Amplifier small signal equivalent circuit

To analyze this configuration, we first completed in September down the nodal equations: To analyze this configuration, the first thing that sets the Full nodal equations:

, the nodal equations Can Be rewrite in a more homogeneous form:

Using the Relationship Using the relationship

, nodal equations can be written in a more homogeneous:

or Eliminating v from the last two nodal equations we find That The or elimination of V
the last two nodal equations we find that

and if we substitute this expression Into The first nodal equation we find That and substituting this expression into the first equation we found that nodal



Finally, substituting These two expressions Into the second nodal Following equation we find the expression for the voltage gain: _{Finally, substitution of these expressions in the equation of the second node is the following expression for the voltage gain:}




When
When

you reduce this expression to

this reduces to

When

When

• But but Reduced to it comes down to

• Grounded Common Collector Amplifier or (current circuit configuration ) Grounded common receiver or amplifier (real circuit configuration) CE (Emitter-Follower) Amplifier Small-Signal Equivalent Circuit

CE ("emitter follower") amplifier small-signal equivalent circuit

Again to analyze this configuration, we first completed in September down the nodal equations: again to analyze this configuration, the first thing that sets the full nodal equations:

Again using the Relationship Again using the relationship

, the nodal Can Be rewrite equations in a more homogeneous form: , nodal equations can be written in a more homogeneous:

Substituting the second nodal Into The first equation Following we find the expression for the voltage gain: Substituting the second node in the first we find the following expression for the voltage gain:

A "trickly" Calculation is required to Obtain the output impedance. To do so we first shut off the input voltage and Then Apply test voltage source, v x , to the output terminal. Under These Circumstances, the current Into the output terminal is Given by: A "trickly" calculation is required to obtain the output impedance. To do this, first turn off the input voltage and then apply the source voltage test, v x, to the output terminal. In these circumstances, the current in the output terminal is given by:

Therefor, the

Relatively low output impedance is Given by:
Therefore, the output impedance relatively low is given by:

Relatively high while the input impedance is Given by _: while the high input impedance relatively _{is given by:}

PREPARED BY: NERWIN REINOSO ANTONIO MORA CI : 17,557,095 EES

SECTION 1