{ "metadata": { "name": "", "signature": "sha256:58df60b52752f2da1373bbe228598764eb4342aba17c209c22ffab14d8498063" }, "nbformat": 3, "nbformat_minor": 0, "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": {} } ] }