ELEC 350 Electronics I Fall 2011Final Exam InformationRough breakdown of topic coverage:40-70% BJT fundamentals and biasing, MOSFET small-signal modeling10-20% MOSFET fundamentals and biasing10-20% Diodes (pn-junction diodes, zeners, attenuator circuits)10-20% Op-amps, including non-ideal effectsSee the “Course Outcomes” section of the Course Description page at the ELEC 350 web site fora more detailed list of specific competencies that are likely to be assessed.The exam will take place 8:00-11:00 am on Wednesday, December 14 in Dana 113 (Gardner Lecture Hall). The exam will be designed to be approximately 1.5 hours in length, but you will have the full three hours to complete it.You will be allowed to use up to four 8.5 x 11-inch review sheets with text on the front and back of each. There are no restrictions on the material placed on the review sheets. Please note that all review sheets will be collected at the end of the exam.The final exam grade cannot be dropped.Review Topics for Final ExamThe following is a list of topics that could appear in one form or another on the exam. Not all of these topics will be covered, and it is possible that an exam problem could cover a detail not specifically listed here. However, this list has been made as comprehensive as possible. You should be familiar with the topics on the previous review sheets in addition to those listed below.General small-signal modeling-definition of “incremental signal” (fluctuations are a small fraction of bias level)-separation of bias considerations (quiescent levels; output voltage swing range) from small-signal considerations (gain, input and output resistance)-replacement of DC voltage sources with short circuits (because voltage across a DC voltage source can’t change)-replacement of DC current sources with open circuits (because current through a DC current source can’t change)-replacement of large capacitors with short circuits (if capacitive reactance is insignificant at operating frequency)-replacement of large inductors with open circuits (if inductive reactance is very large at operating frequency)-DC voltage sources are typically bypassed at AC (i.e., at signal frequency) using capacitors to ensure that the source acts as an AC ground.-small-signal models of FETs and BJTs are only valid when device operates in the constant-current region (saturation for MOSFETs, active for BJTs)1 of 4-small-signal models are not valid in the cut-off region or in the triode region for FETsor the saturation region for BJTs-derivation of small-signal voltage gain vo/vin-simplifications can sometimes be made in gain expressions when one term is much greater/smaller than another termSmall-signal modeling of MOSFET circuits-gate-source path modeled as an open circuit-small-signal transconductance gmobasic definition: GSGSVvGSDmvigoequivalent formulas (for NMOS devices; similar for PMOS): DntGSDtGSnOVnmIkVVIVVkVkg 22,where LWCLWkkoxnnnoderivations of these formulas-incremental drain-source resistance ro orepresents non-zero slope of iD-vDS characteristic in the saturation regionotypically 20-100 k for MOSFETsocan be much lower for some types of FETsoDAoIVr  , where VA = Early voltage-effect of source degeneration resistor (RS) on gain-common-source (CS) and common-drain (CD) amplifiersInternal structure of bipolar junction transistor (BJT)-npn: thin p-type base sandwiched between n-type emitter and collector-pnp: opposite of npnQualitative understanding of operation of BJT-turn-on voltage (VD0) of base-emitter junction (approx. 0.7 V for Si)-effect of changing base current iB-effect of changing collector-emitter voltage vCE-directions and polarities of important currents and voltages (iB, iC, iE, vBE, vCE)-thin base region required to allow electrons (npn) or holes (pnp) to flow from emitter to collector-emitter more heavily doped than base – allows base to fill with minority carriers whenbase current flows-base-emitter junction is forward biased if vBE is at turn-on voltage (VD0)-i-v characteristic of B-E junction is the same as that of a pn-junction diode-collector-base junction is usually reverse biased (produces depletion region) or lightlyforward biased-collector current related to base current by iC = FiB in the active region-F = forward DC current gain (values are typically 20-300, but vary among BJT types, even among individual units of a given type within the same manufacturing batch)BJT i-v characteristic (iC vs. vCE for selected values of iB)2 of 4-cut-off region (vBE < VF, where VF = turn-on voltage of BE junction; iB = iC = 0)-active (constant-current) region (iC = iB)-saturation region (vCE ≈ 0.2-0.3 V and iC < iB, but iC is nonzero)npn vs. pnp BJTs-circuit symbols (arrow indicates emitter; arrow of npn is “not pointing in”)-vBE, and vCE of pnp BJTs have negative values in normal operation-iB and iC flow out of base and collector terminals of pnp BJTs-i-v characteristics of npn and pnp BJTs have voltages of opposite signGeneral analysis techniques for BJT circuits-determination of region of operation (cutoff, active, or saturation)-vCE (for npn BJTs) is always positive (negative for pnp)-graphical analysis techniques (load lines) can be applied-vBE = 0.7 V (for npn) in the active and saturation regions-in active region, iC = iB-in saturation region, vCE = vCE|sat ≈ 0.2-0.3 V and iC < iBBJT inverter circuits-can be used as logical NOT gates-transfer characteristic (vo vs. vin) has negative slope (or zero slope in some regions)-BJT version is also called a common-emitter amplifier-has an almost linear transfer characteristic in active regionBJT biasing circuits-design for quiescent output voltage, collector current, and/or voltage drop across emitter resistor (if present)-usually bias BJT for operation in the active region-must pay attention to swing range of vC (collector node voltage) to avoid cutoff and saturation regionsoin cutoff region, iC = 0; also applies at the boundary between the cutoff and active regionsoactive-saturation boundary defined by (for npn devices):V3.0.saactive tCEV othe parameter  has strong temperature dependence and device variation-parameter-independent biasing (emitter degeneration) using “4-resistor” bias networkomakes use of negative feedback via emitter degeneration resistoroconsists ofcollector resistor, usually labeled RCemitter resistor, usually labeled