CHAPTER 6 Bipolar Junction Transistors BJTs Figure 6
CHAPTER 6 Bipolar Junction Transistors (BJTs)
Figure 6. 1 A simplified structure of the npn transistor. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
Figure 6. 2 A simplified structure of the pnp transistor. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
Figure 6. 3 Current flow in an npn transistor biased to operate in the active mode. (Reverse current components due to drift of thermally generated minority carriers are not shown. ) Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
Figure 6. 9 Modeling the operation of an npn transistor in saturation by augmenting the model of Fig. 6. 5(c) with a forward conducting diode DC. Note that the current through DC increases i. B and reduces i. C. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
Figure 6. 10 Current flow in a pnp transistor biased to operate in the active mode. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
Figure 6. 12 Circuit symbols for BJTs. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
Figure 6. 13 Voltage polarities and current flow in transistors biased in the active mode. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
Figure 6. 18 Large-signal equivalent-circuit models of an npn BJT operating in the active mode in the common-emitter configuration with the output resistance ro included. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
Figure 6. 32 Biasing the BJT amplifier at a point Q located on the active-mode segment of the VTC. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
Figure 6. 34 Graphical construction for determining the VTC of the amplifier circuit of Fig. 6. 33(a). Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
Figure 6. 38 Illustrating the definition of rπ and re. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
Figure 6. 39 The amplifier circuit of Fig. 6. 36(a) with the dc sources (VBE and VCC) eliminated (short-circuited). Thus only the signal components are present. Note that this is a representation of the signal operation of the BJT and not an actual amplifier circuit. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
Figure 6. 40 Two slightly different versions of the hybrid-π model for the small-signal operation of the BJT. The equivalent circuit in (a) represents the BJT as a voltage-controlled current source (a transconductance amplifier), and that in (b) represents the BJT as a currentcontrolled current source (a current amplifier). Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
Figure 6. 47 The hybrid- small-signal model, in its two versions, with the resistance ro included. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
Table 6. 4 Small-Signal Models of the BJT Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
Figure 6. 48 The three basic configurations of BJT amplifier. The biasing arrangements are not shown. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
Figure 6. 51 Performing the analysis directly on the circuit with the BJT model used implicitly. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
Figure 6. 52 The CE amplifier with an emitter resistance Re; (a) Circuit without bias details; (b) Equivalent circuit with the BJT replaced with its T model. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
Figure 6. 59 Two obvious schemes for biasing the BJT: (a) by fixing VBE; (b) by fixing IB. Both result in wide variations in IC and hence in VCE and therefore are considered to be “bad. ” Neither scheme is recommended. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
Figure 6. 60 Classical biasing for BJTs using a single power supply: (a) circuit; (b) circuit with the voltage divider supplying the base replaced with its Thévenin equivalent. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
Figure 6. 62 (a) A common-emitter transistor amplifier biased by a feedback resistor RB. (b) Analysis of the circuit in (a). Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
Figure 6. 64 Basic structure of the circuit used to realize single-stage, discrete-circuit BJT amplifier configurations. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
Figure 6. 66 (a) A common-emitter amplifier with an emitter resistance Re. (b) Equivalent circuit obtained by replacing the transistor with its T model. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
Figure 6. 69 Sketch of the magnitude of the gain of a CE amplifier versus frequency. The graph delineates the three frequency bands relevant to frequency-response determination. Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
Figure P 6. 29(a) Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
Figure P 6. 30 Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
Figure P 6. 34 Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
Figure P 6. 52 Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
Figure P 6. 62 (c) Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
Figure P 6. 107 Microelectronic Circuits, Sixth Edition Sedra/Smith Copyright © 2010 by Oxford University Press, Inc.
- Slides: 42