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Circuitul nestabilizat:
Figura1
Circuitul stabilizat:
Figura 2
Pentru circuitele stabilizatoare folosim modelele :
Ri=10M ; Au=13% ; Ro<100 ; fj£10Hz ; fi³1MHz ;
Am ales pentru tranzistorul Tec-J modelul 2N3819:
Vp=−3V ; Vpmax=−8V
IDSSmin=2mA ; IDSSmax=20mA
iD=0.8IDSS=1.8mA.
Pentru tranzistoarele Q2 si Q3 modelul 2N2222
b
uBE0=0.6V
Am ales pentru dioda zener modelul BZX55-B5V6:
uz=5.6V
Iz=5V ;
iD=iC3=1.8mA - constant
iD=IDSS(1-uGS/Vp)2 Þ uGS=Vp(1∓√iD/IDSS) Þ
uGSmin=-0.15V
uGSmax=-5.6V ;
uDS≥∣uGS-Vp∣max Þ uDS³7.85V
Vas+³uoM-VPmax ³11V
½Vas-½³uoM+uZoM+uCE3m+uGSm=10.45V
Vas+= ½Vas-½=12V
iD=1.8mA
uDS= Vas++ uGSmin=11.85V
ÞPSFJ1(1.8mA ;11.85V)
Calculam rezistentele
R1=10MW
RL=1kW
U(R3)=uZ , iD=iC3=iR3
R3=uz01/iR3=3.11kW → 3.3kW 5% - rezist. standardizata
u R2)= ½Vas-½-uD01-uZ=5.8V
R2= u R2)/iZ=1.16 kW → 1.3 kW
iC2 R4║RL=uoM
iC2 R4=½Vas-½-uBE2-uGsmin Þ R4=2.75 kW → 2.7 kW 5% , iC2=4.2mA;
uCE3=- uGSmin-uZ- Vas-=6.55V
PSF Q3(1.8mA ;6.55V)
uCE2=uDS+uBE2=12.45V
PSF Q2 (4.2mA ;12.45V) ;
Calculam puterile maxime disipate pe rezistente
Pd(R2)=R2iZ2=29mW→ 50mW
Pd(R3)= R3 iC32=11mW→ 25mW
u(R4)=uCE2, i(R4)= u(R4)/ R4=4.6mA
Pd(R4)= R4 i(R4)2=58mW→ 75mW ;
gm1=½(2IDSS/Vp)(1-uGS/Vp)┃=1.27mA/V
gm2=iC2/ VT= iC240=168mA/V
rb'e =b/ Gm2=100/168=0.595kΩ
Figura 1
U0=(gm1uGS+gm2ub'e) R4║RL
ub'e= gm1 uGSrb'e
ui= uGS+ ub'e+u0
u= u0 /ui=0.98
Ri=R1=10MΩ
R0=(1/gm1+ rb'e)/(1+b W<100W
Calculam capacitatile la frecvente joase :
f₌√(f12+f22) f1=1/2∏R1C1 f2=1/2∏RLC2
Au(jω)=[AujωC1(R1+Rg)]/[1+jω C1(R1+Rg)] [ jωC2(RL+R0)]/[ 1+jω C2(RL+ +R0)]
Au(jω)= Au[(jf /f1)/(1+ jf /f1)] [(jf/f2)/( 1+ jf /f2)]
2f4=(f12+f2)(f22+f2) dar f≤10HZ
f1<<f2 ⇒ f1=0.1HZ ; f2≃9.9HZ
C1=1/2∏R1f1=159nF ; C2=1/2∏RLf2=16mF
La frecvente inalte
Pentru CGS u=uGS
Figura 2
-iR1║Rg=uGS+ub'e+( ub'e/rb'e+gm2ub'e) R4║RL
i(-R1║Rg- rb'e- R4║RL- rb'egm2R4║RL)=u(1+ rb'egm1+ gm1+
+ rb'egm1gm2R4║RL)
RP1=½u/i½ W
fP1=1/2∏CGSRp1=79.6MHZ
CGS=8pF ;
Pentru CGD:
Figura6
U=iRg║R1 ; RP2= Rg║R1=1kW
fP2=1/2∏CGDRp2=39.8MHZ ;
Pentru Cb'e:
Figura7
Vg=0 Þii=0
ÞuGS=
gm1 uGS=0
ub'e=-u
(ub'e/rb'e+i+gm2ub'e) R4║RL=- ub'e
RP3=½u/i½ W
Cb'e=25pF+gm2/2∏fT=132pF
fP3=1/2∏13210-126=201MHZ ;
Pentru Cb'c:
Figura8
Vg=0 ; ii=0
RP4≈1/gm1=1000/1.27≃787Ω
fP4=1/2∏810-12787=25.3MHz
Cb'c=8pF
fi=1/(1/fP1+1/fP2+1/fP3+1/fP4)=12.2MHZ ;
*PROIECT DCE2
**** CIRCUIT DESCRIPTION
j1 3 2 4 j2n3819
q2 3 4 8 q2n2222
q3 4 6 7 q2n2222
r1 2 0 10Meg
r2 6 0 1.3k
r3 7 11 3.3k
r4 8 11 2.7k
rl 9 0 1k
dz1 10 6 d1n752
d1 10 11 d1n4148
c1 1 2 220n
c2 8 9 22u
vasp 3 0 12v
vasm 11 0 -12v
vg 1 0 ac 10mV sin(0 3v 1kHz)
.tran 0.25ms 5ms 0 20us
.ac dec 100 1Hz 100Meg
.op
.lib library/dce.lib
.lib library/bipolar.lib
.lib library/diode.lib
.probe
.end
**** DIODES
NAME dz1 d1
MODEL d1n752 d1n4148
ID -4.40E-03 4.40E-03
VD -5.56E+00 7.04E-01
REQ 4.25E+00 5.87E+00
CAP 4.37E-11 2.05E-09
**** BIPOLAR JUNCTION TRANSISTORS
NAME q2 q3
MODEL q2n2222 q2n2222
IB 2.57E-05 9.97E-06
IC 4.86E-03 1.69E-03
VBE 6.84E-01 6.57E-01
VBC -1.01E+01 -7.60E+00
VCE 1.08E+01 8.26E+00
BETADC 1.89E+02 1.69E+02
GM 1.85E-01 6.49E-02
RPI 1.10E+03 2.86E+03
RX 1.00E+01 1.00E+01
RO 1.73E+04 4.83E+04
CBE 1.14E-10 6.34E-11
CBC 2.93E-12 3.21E-12
CBX 0.00E+00 0.00E+00
CJS 0.00E+00 0.00E+00
BETAAC 2.03E+02 1.86E+02
FT 2.53E+08 1.55E+08
**** JFETS
NAME j1
MODEL j2n3819
ID 1.71E-03
VGS -1.86E+00
VDS 1.01E+01
GM 3.02E-03
GDS 3.77E-06
CGS 1.65E-12
CGD 6.32E-13
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