Transistor vlves
1) Circuit equivalent of a BJT to the vlves:
It is obtained easy from the 
equations
which to they time is obtained developing in series of Taylor two
functions (vb andthe c) of the same brace of variable (ib, vc).
2) Nomenclature of the pedici of the hybrid parameters in the model of the transistor:
1ª the letter characterizes the physical truth that stà analyzing itself, it can be one of following:
= input the r = reverse f = forward or = output
2ª the letter characterizes the configuration of the transistor to which it refers to us:
b = base comune c = collector comune common emettitore and =
3) hIE :
4) hking :
5) hfe :
6) hoe :
7) Variation of the hybrid parameters:
They can vary with the temperature, with the job point and with the frequency, pack-saddles to think that the hybrid parameters can be gain you from the characteristic curves, the supplied values are in kind reported to the ambient temperature and the frequency of 1khz.
8) Amplification in current for the configuration to common emettitore:
Replacing 
in 
the
and collectingthe c it is
obtained 
, it assumes the its maximum value To@hfe the per 0<RL< 104 .
9) Resistance of income for the configuration to common emettitore:
Replacing in 
the
can 
be gained that being 
can be replaced in 
the therefore collectingthe b is had:
500 typical values areW £ R the £ 1000W .
10) Amplification in tension for the configuration to common emettitore:
The expression of Tov in function of i hybrid parameters can be determined in following the two ways:
to) 
b) one gainsthe b from the and
it is replaced in 
the therefore collecting
the terms in vce and the
terms in vbe it is obtained
it is observed moreover that Tov andi they have opposite sign.
11) Resistance of escape for the configuration to common emettitore:
It is necessary to cortocircuitare the generator of
tension vs and to remove RL , to the income mesh the equation is
had 
from which it gainsthe b and it is replaced in the ,
collectingthe c and vce obtains 
inverting, simplifying and still inverting ha 
.
12) typical Values of the amplification in current for the 3 configurations of the transistor:
COMMON EMETTITORE: 30 ¸ 100
BASE COMMON : 0,93 ¸ 0.99
COMMON COLLECTOR: 30 ¸ 100
13) typical Values of the resistance of R income for the 3 configurations of the transistor:
COMMON EMETTITORE: 500 ¸ 1000
BASE COMMON : 50 ¸ 200
COMMON COLLECTOR: 20K ¸ 100K
14) typical Values of the amplification in tension for the 3 configurations of the transistor:
COMMON EMETTITORE: 300 ¸ 600
BASE COMMON : 500 ¸ 800
COMMON COLLECTOR: 0.95 ¸ 0.95
15) typical Values of the resistance of R escapeor for the 3 configurations of the transistor:
COMMON EMETTITORE: 50K
BASE COMMON : 300K
COMMON COLLECTOR: 500
16) Model to hybrid parameters reduced and conditions of validity:
In short they eliminate from the equivalent outline the generator of tension in income in how much hking @ 10-4 is negligible, as also the resistance mails in parallel to escape 1/hoe @ 10-5 .
17) Theorem of Thevenin:
Whichever linear net to 2 clips can be replaced from a generator of tension of equal value to the tension to empty between the two clips in series with the stiffness of escape seen from that door.
18) Theorem of Norton:
Whichever linear net to 2 finishes them can be replaced from a generator of current of equal value alla current short parallel circuit on the credit side stiffness of escape seen from those clips.
19) Corollario of the theorem of Thevenin and Norton:
The value of the stiffness between two points of a circuit is equal to the relationship between the empty tension to between those two points and the current short circuit.
20) Theorem of Miller:
If the relationship between the tensions in two various
points 1 is famous and 2 of a circuit then the Z' resistance can be
replaced mails between 1 and 2 with two resistances, one between 1 and
mass of 
value and the other between 2 and mass
of value 
, being 
.
21) Duale of the theorem of Miller:
If a quadripolo is had in which a node is towards mass
through a Z' resistance which is common to two distinguished meshes,
then it can be removed the resistance towards mass and be put of
others two, one on the node the 1 of value 
and other on node 2 of value 
being 
.
22) Circuit to high stiffness of income with bootstrapping:
The configuration to common emettitore with resistance of
emettitore bypassata from condenser Cand does not introduce a stiffness of 
income, using the automatic polarization, the stiffness
seen from the generator is but the much lowest one and is worth 
. It can not directly be obviated to the
problem maintaining the advantages of the automatic polarization
connecting the common pointto R
1and R 2 to
the base but through a resistance R3 , in such case in fact the resistance seen from the
generator becomes 
that can be increased
through R3. The
resistance of income increases ulteriorly if cortocircuita through one
condenser C the common point to R1 and 2R and the
emettitore, applying Miller is had 
in fact that
being Tov@1 is reduced to 
where 
.
23) hybrid Parameters of the Darlington logon:
writes the expression
of 
, replacing 
e 
where 
and 
, collecting the terms inthe b is obtained 
replaces 
in 
the collectingthe b is obtained 
24) Analysis of the â?emitter followerâ? of Darlington type:
The external parameters come calculate to you considering the Darlington as an only having transistor the hybrid parameters previously calculates to you and replacing in the outline the hybrid circuit equivalent of the same one.
replacing 
in the expression of the currentthe 0 that slides in Rand is obtained 
.
It is observed that the gain in current is higher regarding
single the pursuer
replacing and in the
expression ofthe v the
relative one to the income mesh and collectingthe
b is obtained 
. It is
observed that the resistance of income is higher regarding single the
pursuer.
is observed that the gain in tension is more far
away from the unit regarding single the pursuer.
replaces 
is in the expression ofthe 0 that slides in Rand that in the expression ofthe b deducted from the income mesh, this last one goes then
replaced in before obtaining 
. It is
observed that the resistance of escape is lower regarding single the
pursuer.
25) Analysis simplified of the â?emitter followerâ? of Darlington type:
is gained observing
that 
and of resto 
the
, replacing is obtained 
is gained remembering that the resistance of
income of single a pursuer of emettitore is 
therefore calculating it from the income towards the escape and
considering that the resistance of escape of first the pursuer is the
resistance of income of the second has 
R0
is gained remembering that the resistance of escape of single a
pursuer is 
but the RS of according to pursuer coincides with the
resistance of escape of the first one for which replacing to chain 
is had.
26) Darlington Logon with bootstrapping:
It is necessary to consider that to Q1 collector current is demanded one much lowland and
therefore the current is not more negligible that gives the base goes
towards the collector, this determines that the is not more
negligible 
resistenza mail between the base and
the collector who therefore limits the maximum value of the resistance
of income of the Darlington being 
, in order to
render it inoperosa that that is made is to place a potential
difference them null to its heads, connecting the collector to the
escape through one ability C0 ,
in such a way applying Miller obtains 
being 
(in fact 
) where R' is the calculate resistance of
income for the Darlington and is worth 
where
Rand in our case is worth 
.