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{
"metadata": {
"name": "",
"signature": "sha256:5a78eb3c7cc2f82cd21ccad707b4376bdb45f22452d4892c16308b1bdd58f45f"
},
"nbformat": 3,
"nbformat_minor": 0,
"worksheets": [
{
"cells": [
{
"cell_type": "heading",
"level": 1,
"metadata": {},
"source": [
"chapter08:Multistage Amplifiers"
]
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example E1 - Pg 276"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Express the gain in decibel\n",
"#given\n",
"#Powere gain of 1000\n",
"import math\n",
"Pg1=1000.;\n",
"Pgd1=10.*math.log10(Pg1);\n",
"print '%s %.f %s' %(\"Power gain (in dB)=\",Pgd1,\"dB\\n\");\n",
"\n",
"#Voltage gain of 1000\n",
"Vg1=1000.;\n",
"Vgd1=20.*math.log10(Vg1);\n",
"print '%s %.f %s' %(\"Voltage gain (in dB)=\",Vgd1,\"dB\\n\");\n",
"\n",
"#Powere gain of 1/100\n",
"Pg2=1./100.;\n",
"Pgd2=10.*math.log10(Pg2);\n",
"print '%s %.f %s' %(\"Power gain (in dB)=\",Pgd2,\"dB\\n\");\n",
"\n",
"#Voltage gain of 1/100\n",
"Vg2=1./100.;\n",
"Vgd2=20.*math.log10(Vg2);\n",
"print '%s %.f %s' %(\"Voltage gain (in dB)=\",Vgd2,\"dB\\n\");\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Power gain (in dB)= 30 dB\n",
"\n",
"Voltage gain (in dB)= 60 dB\n",
"\n",
"Power gain (in dB)= -20 dB\n",
"\n",
"Voltage gain (in dB)= -40 dB\n",
"\n"
]
}
],
"prompt_number": 1
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example E2 - Pg 276"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Determine power and voltage gain\n",
"#given\n",
"#For Gain = 10 dB\n",
"G=10.;#dB\n",
"Pg1=10.**(G/10.); #taking antilog\n",
"Vg1=10.**(G/20.); #taking antilog\n",
"print '%s %.f %s' %(\"For Gain\",G,\"dB\\n\")\n",
"print '%s %.f %s' %(\"Power gain ratio =\",Pg1,\"\\n\");\n",
"print '%s %.2f %s' %(\"Voltage gain ratio =\",Vg1,\"\\n\");\n",
"\n",
"#For Gain 3 dB\n",
"G=3.;#dB\n",
"Pg2=10.**(G/10.); #taking antilog\n",
"Vg2=10.**(G/20.); #taking antilog\n",
"print '%s %.f %s' %(\"For Gain\",G,\"dB\\n\")\n",
"print '%s %.2f %s' %(\"Power gain ratio =\",Pg2,\"\\n\");\n",
"print '%s %.3f %s' %(\"Voltage gain ratio =\",Vg2,\"\\n\");\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"For Gain 10 dB\n",
"\n",
"Power gain ratio = 10 \n",
"\n",
"Voltage gain ratio = 3.16 \n",
"\n",
"For Gain 3 dB\n",
"\n",
"Power gain ratio = 2.00 \n",
"\n",
"Voltage gain ratio = 1.413 \n",
"\n"
]
}
],
"prompt_number": 2
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example E3 - Pg 277"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Calculate the overall voltage gain\n",
"#given\n",
"import math\n",
"A1=80.\n",
"A2=50.\n",
"A3=30.\n",
"Ad=20.*math.log10(A1)+20.*math.log10(A2)+20.*math.log10(A3);\n",
"\n",
"#Alternatively\n",
"A=A1*A2*A3;\n",
"Ad=20.*math.log10(A);\n",
"print '%s %.2f %s' %(\"The Voltage gain is =\",Ad,\"dB\");\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The Voltage gain is = 101.58 dB\n"
]
}
],
"prompt_number": 3
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example E4 - Pg 283"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Calculate quiescent output voltage and small signal voltage gain\n",
"#given\n",
"#At input Voltage =3V\n",
"Vi1=3.##V #input voltage\n",
"Vbe=0.7##V\n",
"B=250.#\n",
"Vcc=10.##V #Supply\n",
"Re1=1.*10.**3.##ohm\n",
"Rc1=3.*10.**3.##ohm\n",
"Re2=2.*10.**3.##ohm\n",
"Rc2=4.*10.**3.##ohm\n",
"Vb1=Vi1# #Voltage at the base of transistor T1\n",
"Ve1=Vb1-Vbe# #Voltage at the emitter of transistor T1\n",
"Ie1=Ve1/Re1#\n",
"Ic1=Ie1#\n",
"Vc1=Vcc-Ic1*Rc1#\n",
"Vb2=Vc1#\n",
"Ve2=Vb2-Vbe#\n",
"Ie2=Ve2/Re2#\n",
"Ic2=Ie2#\n",
"Vo1=Vcc-Ic2*Rc2#\n",
"print '%s %.1f %s' %(\"The quiescent output voltage(At input Voltage = 3V) is =\",Vo1,\"V\\n\")#\n",
"\n",
"#At input Voltage =3.2 V\n",
"Vi2=3.2##V #input voltage\n",
"Vb1=Vi2# #Voltage at the base of transistor T1\n",
"Ve1=Vb1-Vbe# #Voltage at the emitter of transistor T1\n",
"Ie1=Ve1/Re1#\n",
"Ic1=Ie1#\n",
"Vc1=Vcc-Ic1*Rc1#\n",
"Vb2=Vc1#\n",
"Ve2=Vb2-Vbe#\n",
"Ie2=Ve2/Re2#\n",
"Ic2=Ie2#\n",
"Vo2=Vcc-Ic2*Rc2#\n",
"print '%s %.1f %s' %(\"The quiescent output voltage (At input Voltage =3.2 V) is =\",Vo2,\"V\\n\")#\n",
"\n",
"#Small Signal input and output voltage\n",
"vi=Vi2-Vi1#\n",
"vo=Vo2-Vo1#\n",
"Av=vo/vi#\n",
"print '%s %.f' %(\"The small signal voltage gain is =\",Av)\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The quiescent output voltage(At input Voltage = 3V) is = 5.2 V\n",
"\n",
"The quiescent output voltage (At input Voltage =3.2 V) is = 6.4 V\n",
"\n",
"The small signal voltage gain is = 6\n"
]
}
],
"prompt_number": 4
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example E5 - Pg 296"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Calculate the maximum voltage gain and bandwidth of multistage amplifier\n",
"#FUNCTIONS\n",
"#given\n",
"def prll(r1,r2):\n",
"\tz=r1*r2/(r1+r2)#\n",
"\treturn z\n",
"\n",
"import math\n",
"rin=10.*10.**6.;#ohm #input resistance of JFET\n",
"Rd=10.*10.**3.;#ohm\n",
"Rs=500.;#ohm\n",
"Rg=470.*10.**3.;#ohm\n",
"Rl=470.*10.**3.;#ohm\n",
"Cc=0.01*10.**-6.;#Farad\n",
"Csh=100.*10.**-12.;#Farad\n",
"Cs=50.*10.**-6.;#Farad\n",
"rd=100.*10.**3.;#ohm\n",
"gm=2.*10.**-3.;#S\n",
"Rac2=prll(Rd,Rl);\n",
"Rac1=prll(Rd,Rg);\n",
"Req=prll(rd,prll(Rd,Rl));\n",
"Am=math.ceil(gm*Req);\n",
"Am2=Am*Am; #Voltage gain of two stage amplifier\n",
"print '%s %.f %s' %(\"Voltage gain of two stage amplifier=\",Am2,\"\\n\");\n",
"R_=prll(rd,Rd)+prll(Rg,rin);\n",
"f1=1./(2.*math.pi*Cc*R_); #lower cutoff frequency\n",
"f1_=f1/(math.sqrt(math.sqrt(2.)-1.));\n",
"f2=1./(2.*math.pi*Csh*Req); #upper cutoff frequency\n",
"f2_=f2*(math.sqrt(math.sqrt(2.)-1.));\n",
"BW=f2_-f1_;\n",
"print '%s %.f %s' %(\"Bandwidth=\",BW/1000.,\"kHz\\n\");\n",
"#There is a slight error in f1 due to use of R'(here R_)=479 kohm and in f2 due to approaximation of Req there is a slight variation\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Voltage gain of two stage amplifier= 324 \n",
"\n",
"Bandwidth= 115 kHz\n",
"\n"
]
}
],
"prompt_number": 5
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example E6 - Pg 298"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Calculate the midband voltage gain and bandwidth of cascade amplifier\n",
"#given\n",
"import math\n",
"Am=8.##midband voltage gain of individual MOSFET\n",
"BW=500.*10.**3.#Hz\n",
"f2=BW#\n",
"n=4.#\n",
"A2m=Am**n#\n",
"f2_=f2*(math.sqrt((2.**(1./n))-1.))#\n",
"print '%s %.f %s' %(\"Midband voltage gain =\",A2m,\"\\n\")#\n",
"print '%s %.1f %s' %(\"Overall Bandwidth =\",f2_/1000,\"kHz\")#\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Midband voltage gain = 4096 \n",
"\n",
"Overall Bandwidth = 217.5 kHz\n"
]
}
],
"prompt_number": 6
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example E7 - Pg 298"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Calculate the input and output impedance and voltage gain\n",
"#FUNCTIONS\n",
"\n",
"def prll(r1,r2):\n",
"\tz=r1*r2/(r1+r2)#\n",
"\treturn z\n",
"\n",
"import math\n",
"hie=1.1*10.**3.;#ohm=rin\n",
"hfe=120.;#=B\n",
"#the values of Rac2, Zi, Zo are as per diagram\n",
"Rac2=prll(3.3*10**3,2.2*10**3);\n",
"Rac1=prll(6.8*10**3,prll(56*10**3,prll(5.6*10**3,1.1*10**3)));\n",
"Zi=prll(5.6*10**3,prll(56*10**3,1.1*10**3));\n",
"Zo=prll(3.3*10**3,2.2*10**3);\n",
"print '%s %.3f %s %s %.2f %s' %(\"Input Resistance =\",Zi/1000,\"kohm\\n\",\"\\nOutput Resistance =\",Zo/1000,\"kohm\");\n",
"Am2=-hfe*Rac2/(hie);\n",
"Am1=-hfe*Rac1/(hie);\n",
"Am=Am1*Am2;\n",
"Am=20.*math.log10(Am);\n",
"print '%s %.2f %s' %(\"\\nThe Overall Voltage gain is\",Am,\"dB\");\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Input Resistance = 0.905 kohm\n",
" \n",
"Output Resistance = 1.32 kohm\n",
"\n",
"The Overall Voltage gain is 81.97 dB\n"
]
}
],
"prompt_number": 7
}
],
"metadata": {}
}
]
}
|
