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{
"metadata": {
"name": "",
"signature": "sha256:efde35bc6b39332bcbdd0902e3c4730008212f1e0c635f78b359c0a32b2006c0"
},
"nbformat": 3,
"nbformat_minor": 0,
"worksheets": [
{
"cells": [
{
"cell_type": "heading",
"level": 1,
"metadata": {},
"source": [
"Chapter10:Feedback in Amplifiers"
]
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example E1 - Pg 368"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Determine the gain of feedback amplifier\n",
"#given\n",
"A=100.;#internal gain\n",
"B=0.1;#feedback factor\n",
"Af=A/(1.+A*B);\n",
"print '%s %.2f %s' %(\"The gain of feedback amplifier =\",Af,\"\\n\");\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The gain of feedback amplifier = 9.09 \n",
"\n"
]
}
],
"prompt_number": 1
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example E2 - Pg 368"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Determine the gain of feedback amplifier in dB\n",
"#given\n",
"import math\n",
"Ad=60.;#dB #internal gain in dB\n",
"A=10.**(Ad/20.); #internal gain\n",
"B=1./20.;#feedback factor\n",
"Af=A/(1.+A*B);\n",
"Afd=20.*math.log10(Af);\n",
"print '%s %.2f %s' %(\"The gain of feedback amplifier =\",Afd,\"dB\");\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The gain of feedback amplifier = 25.85 dB\n"
]
}
],
"prompt_number": 2
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example E3 - Pg 368"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Calculate the percentage of output fed back to input\n",
"#given\n",
"A=600.;#internal gain\n",
"Af=50.;#gain of feedback amplifier\n",
"B=(A/Af-1.)/A;\n",
"print '%s %.3f %s' %(\"The percentage of output fed back to input =\",B*100,\"percent\");\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The percentage of output fed back to input = 1.833 percent\n"
]
}
],
"prompt_number": 3
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example E4 - Pg 368"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Calculate the internal gain and percentage of output fed back to input\n",
"#given\n",
"Af=80.;#gain of feedback amplifier\n",
"Vi=0.05;#V#input with feedback\n",
"Vi_=4.*10.**-3.;#V#input without feedback\n",
"Vo_=Af*Vi;\n",
"A=Vo_/Vi_;\n",
"print '%s %.f %s' %(\"The internal gain is =\",A,\"\\n\");\n",
"B=(A/Af-1.)/A;\n",
"print '%s %.2f %s' %(\"The percentage of output fed back to input =\",B*100,\"percent\\n\");\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The internal gain is = 1000 \n",
"\n",
"The percentage of output fed back to input = 1.15 percent\n",
"\n"
]
}
],
"prompt_number": 4
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example E5 - Pg 369"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Calculate the gain with and without feedback and feedback factor\n",
"#given\n",
"Vo_=5.;#V #output voltage\n",
"Vi=0.2;#V #input with feedback\n",
"Vi_=0.05;#V #input without feedback\n",
"A=Vo_/Vi_;\n",
"Af=Vo_/Vi;\n",
"print '%s %.f %s' %(\"The gain without feedback is =\",A,\"\\n\");\n",
"print '%s %.f %s' %(\"The gain with feedback is =\",Af,\"\\n\");\n",
"B=(A/Af-1.)/A;\n",
"print '%s %.f %s' %(\"The feedback factor =\",B*100,\"percent\\n\");\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The gain without feedback is = 100 \n",
"\n",
"The gain with feedback is = 25 \n",
"\n",
"The feedback factor = 3 percent\n",
"\n"
]
}
],
"prompt_number": 5
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example E6 - Pg 369"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Calculate the gain of feedback amplifier and feedback factor\n",
"#given\n",
"A=100.; #internal gain\n",
"N=20.;#dB #negative feedback\n",
"B=(10.**(-N/(-20.))-1.)/A; #taking antilog\n",
"Af=A/(1.+A*B);\n",
"print '%s %.f %s' %(\"The feedback factor =\",B*100,\"percent\\n\");\n",
"print '%s %.f %s' %(\"The gain of the feedback amplifier is =\",Af,\"\\n\");\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The feedback factor = 9 percent\n",
"\n",
"The gain of the feedback amplifier is = 10 \n",
"\n"
]
}
],
"prompt_number": 6
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example E7 - Pg 371"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Calculate percentage change in the overall gain\n",
"#given\n",
"A=1000.;#internal gain\n",
"N=40.;#dB#negative feedback\n",
"D=10.**((-N)/-20.);#D=(1+AB)desensitivity\n",
"dA_A=10.;#percent#dA/A\n",
"dAf_Af=dA_A/D;#dAf/Af\n",
"print '%s %.1f %s' %(\"The percentage change in the overall gain =\",dAf_Af,\"percent\");\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The percentage change in the overall gain = 0.1 percent\n"
]
}
],
"prompt_number": 7
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example E8 - Pg 371"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Calculate percentage change in the overall gain\n",
"#given\n",
"Adb=60.;#dB#internal gain in dB\n",
"B=0.005;#feedback factor\n",
"A=10.**(Adb/(20.));#taking antilog\n",
"dA_A=-12.;#percent #dA/A\n",
"D=(1.+A*B);#D=(1+AB)desensitivity\n",
"dAf_Af=dA_A/D;#dAf/Af\n",
"print '%s %.f %s' %(\"The percentage change in the overall gain reduces by =\",-dAf_Af,\"percent\");\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The percentage change in the overall gain reduces by = 2 percent\n"
]
}
],
"prompt_number": 8
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example E9 - Pg 374"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Determine the input resistance of feedback amplifier\n",
"#given\n",
"A=250.;#internal gain\n",
"B=0.1;#feedback factor\n",
"Ri=1.1*10.**3.;#ohm #input resistance\n",
"Rif=Ri*(1.+A*B);\n",
"print '%s %.1f %s' %(\"The input resistance of feedback amplifier =\",Rif/1000,\"kohm\");\n",
"\n",
"#The ans in book is incorrect due to use of (2+A*B) instead of (1+A*B) the ans in book is 29.7 kohm\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The input resistance of feedback amplifier = 28.6 kohm\n"
]
}
],
"prompt_number": 9
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example E10 - Pg 374"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#Calculate the percentage of negative feedback to input\n",
"#given\n",
"Adb=60.;#dB #internal gain in dB\n",
"A=10.**(Adb/(20.)); #taking antilog\n",
"Ro=12.*10.**3.;#ohm #output resistance\n",
"Rof=600.;#ohm\n",
"B=(Ro/Rof-1.)/A;\n",
"print '%s %.1f %s' %(\"The percentage of negative feedback to input =\",B*100,\"percent\");\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The percentage of negative feedback to input = 1.9 percent\n"
]
}
],
"prompt_number": 10
}
],
"metadata": {}
}
]
}
|
