EC6201_uw

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I. Input impedance (h ic ): It is defined as the ratio of change in input voltage (base voltage) to change in input current (base current) with the output voltage (emitter voltage) is kept constant. II. Output admittance (h oc ): It is defined as the ratio of change in output current (emitter current) to change in output voltage (emitter voltage) with the input current (base current) is kept constant. III. Forward current gain (h fc ): It is defined as the ratio of change in output current (emitter current) to change in input current (base current) with the output voltage (emitter voltage) is kept constant. IV. Reverse voltage gain (h rc ): It is defined as the ratio of change in input voltage (base voltage) to change in output voltage (emitter voltage) with the input current (base current) is kept constant. A comparison of CB, CE and CC Configurations
Hybrid-Pi Model Bipolar transistors are commonly used in circuits that amplify time-varying or sinusoidal signals. In these linear amplifier circuits, the transistor is biased in the forward-active region and small sinusoidal voltages and currents are superimposed on dc voltages and currents. In these applications, the sinusoidal parameters are of interest, so it is convenient to develop a smallsignal equivalent circuit of the bipolar transistor using the small-signal admittance parameters of the pn junction. Figure 1a shows an npn bipolar transistor in a common emitter configuration with the smallsignal terminal voltages and currents. Figure 1b shows the cross section of the npn transistor. The C, B, and E terminals are the external connections to the transistor, while the C', B', and E' points are the idealized internal collector, base, and emitter regions. We can begin constructing the equivalent circuit of the transistor by considering the various terminals individually. Figure 2a shows the equivalent circuit between the external input base terminal and the external emitter terminal. The résistance rb is the series resistance in the base between the external base terminal B and the internal base region B'. The B'-E' junction is forward biased, so C, is the junction diffusion capacitance and r, is the junction diffusion resistance. The diffusion capacitance C is, the diffusion resistance r, The values of both parameters are functions of the junction current. These two elements are in parallel with the junction capacitance, which is C. Finally, r is the series resistance between the external emitter terminal and the internal emitter region. This resistance is usually very small and may be on the order of 1 to2 Ω. Figure 2b shows the equivalent circuit looking into the collector terminal. The r, resistance is the series resistance between the external and internal collector connections and the capacitance C, is the junction capacitance of the reverse-biased collector-substrate junction Figure 3 shows the equivalent circuit of the reverse-biased B'-C' junction. The C, parameter is the reverse-biased junction capacitance and r, is the 1 reverse-biased diffusion resistance.
Page 1 and 2: FATIMA MICHAEL COLLEGE OF ENGINEERI
Page 3 and 4: temperature leads to an increase in
Page 5 and 6: THE PN JUNCTION The total charge on
Page 7 and 8: If one side of crystal pure semicon
Page 9 and 10: Forward currents V V P ( 0 ) p ( e
Page 11 and 12: If V >> V T then the term e (-V/ Ƞ
Page 13 and 14: (a) Exess hole concentration varyin
Page 15 and 16: As soon as equilibrium is disturbed
Page 17 and 18: Electrons forming covalent bonds of
Page 19 and 20: Forward recovery time is defined is
Page 21 and 22: In clamping networks used as DC Res
Page 23 and 24: Transistor currents - The arrow is
Page 25 and 26: • A very small number of carriers
Page 27 and 28: As the voltages applied to the base
Page 29 and 30: (5) The collector current is theref
Page 31 and 32: In CB configuration a variation of
Page 33 and 34: Input Characteristics It is defined
Page 35 and 36: Transistor parameters in CE configu
Page 37: To determine input characteristics,
Page 42: The h-parameter model is defined by
Page 45 and 46: We can also write the emitter curre
Page 47 and 48: Gummel-Poon Model The Gummel-Poon m
Page 49 and 50: Multi Emitter Transistor (Transisto
Page 51 and 52: If the channel is doped with a dono
Page 53 and 54: • With a steady gate-source volta
Page 55 and 56: The metal-oxide semiconductor field
Page 57 and 58: Fig 2. n - channel depletion type M
Page 59 and 60: The SiO 2 layer is still present to
Page 61 and 62: Fig 3. Change in channel and deplet
Page 63 and 64: UNIT IV SPECIAL SEMICONDUCTOR DEVIC
Page 65 and 66: Zener diode A Zener diode is a type
Page 67 and 68: VARACTOR DIODE A varactor diode is
Page 69 and 70: ENERGY BAND DIAGRAM Energy-band dia
Page 71 and 72: - Hence tunneling current is maximu
Page 73 and 74: laser (often another diode laser) a
Page 75 and 76: LDR: A photoresistor or light-depen
Page 77 and 78: UNIT V POWER DEVICES AND DISPLAY DE
Page 79 and 80: Silicon Controlled Rectifier (SCR)
Page 81 and 82: The SCR can be made to conduct heav
Page 83 and 84: Construction The diac can be constr
Page 85 and 86: When switch S is closed, the gate c
Page 87 and 88: There is also the existence of two
Page 89 and 90:
A digit on an LCD display may have
Page 91 and 92:
‣Used for image sensing circuits.
Page 93 and 94:
same figure, a sketch of the photot
Page 95 and 96:
Fig 1. (a) cross section; (b) top v
Page 97 and 98:
phototransistor in the same package
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