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{
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"worksheets": [
{
"cells": [
{
"cell_type": "heading",
"level": 1,
"metadata": {},
"source": [
"Chapter5:MICROWAVE TRANSISTORS AND TUNNEL DIODES"
]
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Ex5.1.1:pg-195"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#(a) Program to find the mutual conductance gm. \n",
"ic=6*(10**-3) #Collector Current in ampere\n",
"vt=26*(10**-3) #vt=26mV at 300k is the voltage equivalent of temperature \n",
"gm=ic/vt #the mutual conductance is gm=(ic/vt) \n",
"print\"The mutual conductance is gm(in mho)=\",round(gm,2),\"mho\" \n",
"\n",
"#(b) Program to find the input conductance gb and resistance R \n",
"hfe=120 #hfe= common-emitter current gain factor\n",
"gb=round(gm,2)/hfe #input conductance in mho\n",
"Ri=1/gb #Resistance in ohms\n",
"print\"Input conductance gb(in mho)=\",\"{:.2e}\".format(gb),\"mho\"\n",
"print\"Input resistance Ri (in ohms)=\",int(Ri),\"ohms\"\n",
"\n",
"#(c)Program to find the electron diffusion coefficient Dn\n",
"un=1600 #electron Mobility in cm2/V.s\n",
"Dn=un*vt # Dn=un*kt/q=un*26*(10**-3)\n",
"print\"Electron diffusion coefficient Dn(in cm2/s)=\",Dn,\"cm2/second\"\n",
"\n",
"#(d)Program to find the diffusion capacitance Cbe\n",
"Wb=(10**-8) #cross sectional area in cm2 \n",
"Cbe=(round(gm,2)*(Wb**2))/(2*Dn)\n",
"Cbe=Cbe/(10**-19) \n",
"print\"Diffusion capacitance Cbe(in pF)=\",round(Cbe,2),\"pF\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The mutual conductance is gm(in mho)= 0.23 mho\n",
"Input conductance gb(in mho)= 1.92e-03 mho\n",
"Input resistance Ri (in ohms)= 521 ohms\n",
"Electron diffusion coefficient Dn(in cm2/s)= 41.6 cm2/second\n",
"Diffusion capacitance Cbe(in pF)= 2.76 pF\n"
]
}
],
"prompt_number": 1
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Ex5.1.2:pg-203"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#(a) Program to find the impurity desities in the emitter,base and collector regions\n",
"NdE=1*(10**19) \n",
"NaB=1.5*(10**17)\n",
"NdC=3*(10**14)\n",
"print\"(a) The impurity densities (in cm-3)are :\"\n",
"print \"NdE=\",\"{:.0e}\".format(NdE),\"cm-3 [the impurity density in the n-type emitter region]\"\n",
"print \"NaB=\",\"{:.1e}\".format(NaB,1),\"cm-3 [the impurity density in the p-type base region]\"\n",
"print \"NdC=\",\"{:.0e}\".format(NdC),\"cm-3 [the impurity density in the n-type collector region]\"\n",
"\n",
"#(b)Program_to_find_the_mobilities_in_the_emitter,base and collector_regions\n",
"upE=80\n",
"unE=105\n",
"upB=400\n",
"unC=1600\n",
"print\"(b) The mobilities(in cm2/v*s)are :\"\n",
"print\"upE=\",upE,\"cm2/V.s [mobility in the emitter]\"\n",
"print\"unE\",unE,\"cm2/V.s [mobility in the emitter]\"\n",
"print\"upB\",upB,\"cm2/V.s [mobility in the base]\"\n",
"print\"unC\",unC,\"cm2/V.s [mobility in thecollector]\"\n",
"\n",
"\n",
"#(c)Program to find the diffusion lengths in the emitter,base and collector regions\n",
"Vt=26*(10**-3) #voltage equivalent of temperature in volt\n",
"DpE=upE*Vt\n",
"DnE=unE*Vt\n",
"DpB=upB*Vt\n",
"DnC=unC*Vt\n",
"print\"(c) The diffusion constants are computed to be:\"\n",
"print\"DpE=\",DpE,\"cm2/s\"\n",
"print\"DnE=\",DnE,\"cm2/s\"\n",
"print\"DpB=\",DpB,\"cm2/s\"\n",
"print\"DnC=\",DnC,\"cm2/s\"\n",
"\n",
"#(d)Program_to_compute_the_equilibrium_densities_in the emitter,base and_collector_regions\n",
"ni=1.5*(10**10)\n",
"pEo=(ni**2)/NdE \n",
"npB=(ni**2)/NaB\n",
"pCo=(ni**2)/NdC\n",
"print\"(d) The equlibrium densities are:\"\n",
"print\"npB=\",\"{:.1e}\".format(npB),\"cm-3\"\n",
"print\"pEo=\",\"{:.2e}\".format(pEo),\"cm-3\" #answer is wrong in book\n",
"print\"pCo=\",\"{:.1e}\".format(pCo),\"cm-3\"\n",
"\n",
"#(e)Program to compute the terminal currents\n",
"print\"(e) The terminal currents are computed as follows:\" \n",
"A=2*(10**-2) # cross-section_area\n",
"q=1.6*(10**-19)\n",
"W=(10**-5) #base_width\n",
"Le=(10**-4) #Diffusion_length_in_emitter\n",
"Ve=.5 #Emitter_junction_voltage\n",
"InE=-(A*q*DnE*(ni**2)*exp(Ve/Vt))/(NaB*W) #Ine=-(Aq*Dp*(ni**2)*(exp(Ve/Vt)-1))/(Le*Nd);\n",
"InE=InE/(10**-3);\n",
"print\" the electron current in the emitter is InE(in mA)=\",round(InE,4),\"mA\"\n",
"IpE=(A*q*DpE*(ni**2)*(exp(Ve/Vt)-1))/(Le*NdE) #Ipe=(A*q*De*peo*(exp(Ve/Vt)-1))/Le =(A*q*Dp*(ni**2)*(exp(Ve/Vt)-1))/(Le*Nd)\n",
"IpE=IpE/(10**-6)\n",
"print\" the hole current in the emitter is IpE(in uA)=\",round(IpE,3),\"uA\"\n",
"Ico=-(A*q*DnE*(ni**2)/(NaB*W))-(A*q*DpE*pEo)/Le\n",
"Ico=Ico/(10**-12)\n",
"print\" the reverse saturation current in the collector is Ico(in pA)=\",round(Ico,3),\"pA\"\n",
"InC=-(A*q*DnE*(ni**2)*exp(Ve/Vt)/(NaB*W))\n",
"InC=InC/(10**-3)\n",
"print\" the electron current which reaches the collector is InC(in mA)=\",round(InC,4),\"mA\"\n",
"IE=(-IpE*(10**-6))+(InE*(10**-3));\n",
"IE=IE/(10**-3);\n",
"print\"the emitter current is IE(in mA)=\",round(IE,3),\"mA\"\n",
"IC=(-Ico*(10**-12))-(InC*(10**-3));\n",
"IC=IC/(10**-3);\n",
"print\"the collector current is IC(in mA)=\",round(IC,3),\"mA\"\n",
"IB=(IpE*(10**-6))-[((InE*(10**-3)))-(InC*(10**-3))]+(Ico*(10**-12));\n",
"IB=IB/(10**-6);\n",
"print\"the current in the base terminal is IB(in uA)=\",round(IB,3),\"uA\"\n",
"print\"NOTE: The recombination-generation currents in the spcae-charge regions are not counted\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"(a) The impurity densities (in cm-3)are :\n",
"NdE= 1e+19 cm-3 [the impurity density in the n-type emitter region]\n",
"NaB= 1.5e+17 cm-3 [the impurity density in the p-type base region]\n",
"NdC= 3e+14 cm-3 [the impurity density in the n-type collector region]\n",
"(b) The mobilities(in cm2/v*s)are :\n",
"upE= 80 cm2/V.s [mobility in the emitter]\n",
"unE 105 cm2/V.s [mobility in the emitter]\n",
"upB 400 cm2/V.s [mobility in the base]\n",
"unC 1600 cm2/V.s [mobility in thecollector]\n",
"(c) The diffusion constants are computed to be:\n",
"DpE= 2.08 cm2/s\n",
"DnE= 2.73 cm2/s\n",
"DpB= 10.4 cm2/s\n",
"DnC= 41.6 cm2/s\n",
"(d) The equlibrium densities are:\n",
"npB= 1.5e+03 cm-3\n",
"pEo= 2.25e+01 cm-3\n",
"pCo= 7.5e+05 cm-3\n",
"(e) The terminal currents are computed as follows:\n",
" the electron current in the emitter is InE(in mA)= -0.2946 mA\n",
" the hole current in the emitter is IpE(in uA)= 0.337 uA\n",
" the reverse saturation current in the collector is Ico(in pA)= -1.312 pA\n",
" the electron current which reaches the collector is InC(in mA)= -0.2946 mA\n",
"the emitter current is IE(in mA)= -0.295 mA\n",
"the collector current is IC(in mA)= 0.295 mA\n",
"the current in the base terminal is IB(in uA)= 0.337 uA\n",
"NOTE: The recombination-generation currents in the spcae-charge regions are not counted\n"
]
}
],
"prompt_number": 11
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Ex5.1.3:pg-206"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#(a) Program to find the mobilities un and up \n",
"un=200\n",
"up=500\n",
"print\"(a) The mobilities(in cm2/V.s )are read from Fig.A-2 in Appendix A as:\"\n",
"print\"un=\",un,\"cm2/V.s [for NdE=5*(10**18) cm-3]\"\n",
"print\"up=\",up,\"cm2/V.s [for Na=5*(10**16) cm-3]\"\n",
" \n",
"#(b) Program to find the diffusion coefficients Dn and Dp \n",
"Vt=26*(10**-3) #Vt=kt/q=voltage equivalent of temperature in volt\n",
"Dn=un*Vt\n",
"Dp=up*Vt\n",
"print\"(b) The diffusion coefficients are:\"\n",
"print\"Dn=\",round(Dn,2),\"cm2/s\" \n",
"print\"Dp=\",round(Dp,1),\"cm2/s\" \n",
"\n",
"#(c) Program to find the emitter efficiency factor y\n",
"W=(10**-3) #Base width in cm\n",
"Le=(10**-2) #Emitter Length in cm\n",
"Na=5*(10**16) #Acceptor density in base region in /cm3\n",
"Nd=5*(10**18) #Donor density in emitter region in /cm3\n",
"y=1/(1+((Dp*Na*W)/(Dn*Nd*Le)))\n",
"print\"(c) The emitter efficiency factor y=\",round(y,3)\n",
"\n",
"#(d) Program to find the transport factor B\n",
"Tn=10**-6 #electron lifetime in seconds\n",
"B=1-((W**2)/(2*Dn*Tn)) #transport factor\n",
"print\"(d) The transport factor B=\",round(B,3)\n",
"\n",
"#(e) Program to find the current gain a\n",
"a=B*y\n",
"print\"(e) The current gain a=\",round(a,2)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"(a) The mobilities(in cm2/V.s )are read from Fig.A-2 in Appendix A as:\n",
"un= 200 cm2/V.s [for NdE=5*(10**18) cm-3]\n",
"up= 500 cm2/V.s [for Na=5*(10**16) cm-3]\n",
"(b) The diffusion coefficients are:\n",
"Dn= 5.2 cm2/s\n",
"Dp= 13.0 cm2/s\n",
"(c) The emitter efficiency factor y= 0.998\n",
"(d) The transport factor B= 0.904\n",
"(e) The current gain a= 0.9\n"
]
}
],
"prompt_number": 15
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Ex5.1.4:pg-211"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"import math \n",
"# Program to determine the maximum allowable power that the transisitor can carry \n",
" \n",
"Xc=1 #Reactance in ohm\n",
"ft=4*(10**9) #Transit-time cut-off frequency in Hertz\n",
"Em=1.6*(10**5) #maximum electric field V/cm\n",
"Vx=4*(10**5) #saturation drift velocity in cm/sec\n",
" \n",
"Pm=(((Em*Vx/(2*math.pi)))**2)/(Xc*(ft**2)); \n",
"print\"The maximum allowable power(in W) that the transisitor can carry is=\",round(Pm,2),\"W\"\n"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The maximum allowable power(in W) that the transisitor can carry is= 6.48 W\n"
]
}
],
"prompt_number": 16
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Ex5.2.1:pg-212"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#(a) Program to determine the latice match present in percent\n",
"\n",
"print\"The latice match present is within 1%\" \n",
" \n",
"#(b) Program to find the conduction-band differential between Ge and GaAs\n",
"X1=4 #electron affinity of Ge in eV\n",
"X2=4.07 #electron affinity of GaAs in eV\n",
"AE=X1-X2\n",
"print\"The conduction-band differential is(in eV)=\",AE,\"eV\" \n",
" \n",
"#(c) Program to find the valence-band differential between Ge and GeA \n",
"Eg2=1.43 #energy gap in GaAs in eV\n",
"Eg1=0.8 #energy gap in Ge in eV\n",
"Ev=Eg2-Eg1-AE\n",
"print\"The valence-band differential is(in eV)=\",Ev,\"eV\" \n",
" "
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The latice match present is within 1%\n",
"The conduction-band differential is(in eV)= -0.07 eV\n",
"The valence-band differential is(in eV)= 0.7 eV\n"
]
}
],
"prompt_number": 17
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Eg5.2.2:pg-215"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#(a) Program to compute the built-in voltage in the p-GaAs side\n",
"Na=6*(10**16) #Acceptor density in p-GaAs side /cm3\n",
"w02=-26*(10**-3)*log(Na/(1.8*(10**6))) \n",
"print\"The built-in voltage(in V) in the p-GaAs side is=\",round(w02,2),\"V\" \n",
" \n",
"#(b) Program to compute the hole mobility\n",
"up=400\n",
"print\"The hole mobility is =\",up,\"cm2/V.s\"\n",
"\n",
"#(c) Program to compute the hole diffusion constant\n",
"Dp=up*26*(10**-3)\n",
"print\"The hole diffusion constant is Dp=\",Dp,\"cm2/s\"\n",
" \n",
"#(d) Program to compute the minority hole density in n-Ge region\n",
"ni=1.5*(10**10)\n",
"Nd=5*(10**18) #Donor density in n-Ge region in /cm3\n",
"pno=(ni**2)/Nd\n",
"print\"The minority hole density (cm-3)in n-Ge is =\",int(pno),\"cm-3\"\n",
" \n",
"#(e) Program to compute the minority electron density in p-GaAs region \n",
"Na=6*(10**16) #acceptor density in p-GaAs region in /cm3\n",
"npo=((1.8*(10**6))**2)/Na\n",
"print\"The minority electron density(in cm-3) in p-GaAs region is =\",npo,\"cm-3\" #answer is wrong in book\n",
" \n",
"#(f) Program to compute the hole diffusion length \n",
"tp=6*(10**-6) #hole lifetime in seconds\n",
"Lp=sqrt(tp*Dp)\n",
"print\"The hole diffusion length(in cm) is =\",\"{:.2e}\".format(Lp),\"cm\"\n",
" \n",
"#(g) Program to compute the emitter-junction current \n",
" \n",
"A=2*(10**-2) #cross section cm2\n",
"VE=1 #bias voltage at emitter junction in Volt\n",
"q=1.6*(10**-19) #charge of electron in V\n",
"l=VE/(26*(10**-3))\n",
"I=(A*q*Dp*pno*(exp(l)-1))/(Lp)\n",
"print\"The emitter-junction current(in A)is =\",round(I,2),\"A\" #answer is wrong in book"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"The built-in voltage(in V) in the p-GaAs side is= -0.63 V\n",
"The hole mobility is = 400 cm2/V.s\n",
"The hole diffusion constant is Dp= 10.4 cm2/s\n",
"The minority hole density (cm-3)in n-Ge is = 45 cm-3\n",
"The minority electron density(in cm-3) in p-GaAs region is = 5.4e-05 cm-3\n",
"The hole diffusion length(in cm) is = 7.90e-03 cm\n",
"The emitter-junction current(in A)is = 9.58 A\n"
]
}
],
"prompt_number": 18
}
],
"metadata": {}
}
]
}
|
