9/12/2013. Microelectronics Circuit Analysis and Design. Modes of Operation. Cross Section of Integrated Circuit npn Transistor

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1 Mcoelectoncs Ccut Analyss and Desgn Donald A. Neamen Chapte 5 The pola Juncton Tanssto In ths chapte, we wll: Dscuss the physcal stuctue and opeaton of the bpola juncton tanssto. Undestand the dc analyss and desgn technques of bpola tanssto ccuts. xamne thee basc applcatons of bpola tanssto ccuts. Neamen Mcoelectoncs, 4e Chapte 5-1 Neamen Mcoelectoncs, 4e Chapte 5-2 Coss Secton of Integated Ccut npn Tanssto Modes of Opeaton Fowad-Actve - juncton s fowad based -C juncton s evese based Satuaton - and -C junctons ae fowad based Cut-Off - and -C junctons ae evese based Invese-Actve (o Revese-Actve) - juncton s evese based -C juncton s fowad based Neamen Mcoelectoncs, 4e Chapte 5-3 Neamen Mcoelectoncs, 4e Chapte 5-4 1

2 npn JT n Fowad-Actve lectons and Holes n npn JT Neamen Mcoelectoncs, 4e Chapte 5-5 Neamen Mcoelectoncs, 4e Chapte 5-6 lectons and Holes n npn JT Wth a + potental acoss the C- temnals. If a postve voltage s appled to the base (>0.6V), the - pn juncton s fowad based. Ccut Symbols and Cuent Conventons The sde electons coss the pn juncton and many electons ae swept to the postve C sde voltage (snce the p base mateal s thn). Ths esults n electon flow fom to C. (Conventonal cuent flow fom C to ). Neamen Mcoelectoncs, 4e Chapte 5-7 Neamen Mcoelectoncs, 4e Chapte 5-8 2

3 Cuent Relatonshps Common-mtte Confguatons C C = C = β = α + = (1 + β ) α β = 1 α Neamen Mcoelectoncs, 4e Chapte 5-9 Neamen Mcoelectoncs, 4e Chapte 5-10 Cuent-Voltage Chaactestcs of a Common-mtte Ccut aly Voltage/Fnte Output Resstance Neamen Mcoelectoncs, 4e Chapte 5-11 Neamen Mcoelectoncs, 4e Chapte

4 DC quvalent Ccut fo npn Common mtte DC quvalent Ccut fo pnp Common mtte Neamen Mcoelectoncs, 4e Chapte 5-13 Neamen Mcoelectoncs, 4e Chapte 5-14 Load Lne Poblem-Solvng Technque: pola DC Analyss 1. Assume that the tanssto s based n fowad actve mode a. V = V (on), I > 0, & I C = βi 2. Analyze lnea ccut. 3. valuate the esultng state of tanssto. a. If V C > V C (sat), assumpton s coect b. If I < 0, tanssto lkely n cutoff c. If V C < 0, tanssto lkely n satuaton 4. If ntal assumpton s ncoect, make new assumpton and etun to Step 2. Neamen Mcoelectoncs, 4e Chapte 5-15 Neamen Mcoelectoncs, 4e Chapte

5 Voltage Tansfe Chaactestc fo npn Ccut Voltage Tansfe Chaactestc fo pnp Ccut Neamen Mcoelectoncs, 4e Chapte 5-17 Neamen Mcoelectoncs, 4e Chapte 5-18 Common mtte wth Voltage Dvde asng and mtte Ressto Mcoelectoncs Ccut Analyss and Desgn Donald A. Neamen Chapte 6 asc JT Amplfes V )] TH = [ R2 /( R1 + R2 V CC Neamen Mcoelectoncs, 4e Chapte 5-19 Neamen Mcoelectoncs, 4e Chapte

6 In ths chapte, we wll: Undestand the concept of an analog sgnal and the pncple of a lnea amplfe. Common mtte wth Tme-Vayng Input Investgate how a tanssto ccut can amplfy a small, tme-vayng nput sgnal. Dscuss and compae the thee basc tanssto amplfe confguatons. Neamen Mcoelectoncs, 4e Chapte 5-21 Neamen Mcoelectoncs, 4e Chapte 5-22 I Vesus V Chaactestc ac quvalent Ccut fo Common mtte v be I Q (1 + ) = I + b VT Neamen Mcoelectoncs, 4e Chapte 5-23 Neamen Mcoelectoncs, 4e Chapte

7 Small-Sgnal Hybd Model fo npn JT g g m βv = I m I = V CQ T T CQ = β Small-Sgnal quvalent Ccut Usng Common-mtte Cuent Gan Phaso sgnals ae shown n paentheses. Neamen Mcoelectoncs, 4e Chapte 5-25 Neamen Mcoelectoncs, 4e Chapte 5-26 Small-Sgnal quvalent Ccut fo npn Common mtte ccut Poblem-Solvng Technque: JT AC Analyss 1. Analyze ccut wth only dc souces to fnd Q pont. 2. Replace each element n ccut wth smallsgnal model, ncludng the hybd model fo the tanssto. 3. Analyze the small-sgnal equvalent ccut afte settng dc souce components to zeo. A = ( g Neamen Mcoelectoncs, 4e Chapte 5-27 v m RC )( + R ) Neamen Mcoelectoncs, 4e Chapte

8 Hybd Model fo npn wth aly ffect Hybd p Model fo pnp wth aly ffect = o V I A CQ Neamen Mcoelectoncs, 4e Chapte 5-29 Neamen Mcoelectoncs, 4e Chapte 5-30 xpanded Hybd Model fo npn h-paamete Model fo npn =h +h =h +h h h e fe = b = β + µ h h e oe µ 1+ β 1 = + µ o Neamen Mcoelectoncs, 4e Chapte 5-31 Neamen Mcoelectoncs, 4e Chapte

9 Common mtte wth Voltage-Dvde as and a Couplng Capacto Small-Sgnal quvalent Ccut Couplng Capacto Assumed a Shot Neamen Mcoelectoncs, 4e Chapte 5-33 Neamen Mcoelectoncs, 4e Chapte 5-34 npn Common mtte wth mtte Ressto Small-Sgnal quvalent Ccut: Common mtte wth R = = ( + +1 ) R b R = R R = + (1 + β ) R 1 2 R b βrc Av = + (1 + β ) R = ( ) + R ( R + R S ) Neamen Mcoelectoncs, 4e Chapte 5-35 Neamen Mcoelectoncs, 4e Chapte

10 R and mtte ypass Capacto dc AND ac Load Lnes: R and mtte ypass Capacto Neamen Mcoelectoncs, 4e Chapte 5-37 Neamen Mcoelectoncs, 4e Chapte 5-38 Poblem-Solvng Technque: Maxmum Symmetcal Swng Common-Collecto o mtte-followe Amplfe 1. Wte dc load lne equaton that elates I CQ and V CQ. 2. Wte ac load lne equatons that elates c and vce 3. In geneal, c = I CQ I C (mn), whee I C (mn) s zeo o othe mnmum collecto cuent. 4. In geneal, v ce = V CQ V C (mn), whee V C (mn) s some specfed mnmum collecto-emtte voltage. 5. Combne above 4 equatons to fnd optmum I CQ and V CQ. Neamen Mcoelectoncs, 4e Chapte 5-39 Neamen Mcoelectoncs, 4e Chapte

11 Small-Sgnal quvalent Ccut: mtte Followe Output Resstance: mtte Followe Ro = R 1+ β o Neamen Mcoelectoncs, 4e Chapte 5-41 Neamen Mcoelectoncs, 4e Chapte