Signals and Amplifiers

Signals and Amplifiers

Microelectronic Circuits, Sixth Edition

Sedra/Smith

Copyright © 2010 by Oxford University Press, Inc.

Signal

v s (t ) = Rs I s (t )

Figure 1.1 Two alternative representations of a signal source: (a) the Thévenin form; (b) the Norton form.


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Figure 1.2 Circuits for Example 1.1.


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Frequency Spectrum of Signals v a (t ) = Va sin(ωt )


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Frequency Spectrum of Signals

Figure 1.5 A symmetrical square-wave signal of amplitude V (multiple sine waves).

Figure 1.6 The frequency spectrum (also known as the line spectrum) of Sedra/Smith Copyright © 2010 by Oxford University Press, Inc. Microelectronic Circuits, Sixth Edition the periodic square wave of Fig. 1.5.

Frequency Spectrum of Signals

Figure 1.7 The frequency spectrum of an arbitrary waveform such as that in Fig. 1.3. Microelectronic Circuits, Sixth Edition

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Analog and Digital Signals

Figure 1.8 Sampling the continuous-time analog signal in (a) results in the discrete-time signal in (b). Microelectronic Circuits, Sixth Edition

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Figure 1.9 Variation of a particular binary digital signal with time.


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Amplifiers

Figure 1.11 (a) Circuit symbol for amplifier. (b) An amplifier with a common terminal (ground) between the input and output ports.

v0(t)=Avin(t) Voltage gain (Av)=v0/vi Microelectronic Circuits, Sixth Edition

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Amplifiers v0(t)=Avin(t) Voltage gain (Av)=v0/vi Voltage gain in decibels=20log|Av| dB Power Gain (Ap)=PL/PI=v0i0/viiin Power gain in decibels=20log|Ap| dB Current Gain (Ai)=i0/iin Current gain in decibels=20log|Ai| dB Ap=AvAi


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Figure 1.13 An amplifier that requires two DC supplies (shown as batteries) for operation.

PL η= x100 PDC Microelectronic Circuits, Sixth Edition

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Figure 1.14 An amplifier transfer characteristic that is linear except for output saturation. Microelectronic Circuits, Sixth Edition

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iC(t)=IC + ic(t) ic(t) =ICsin(ωt)

Figure 1.15 Symbol convention employed throughout the book.


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Circuit Models for Amplifiers v0 = Avo vi

RL R L + R0

Ri vi = v s Ri + Rs Figure 1.16 (a) Circuit model for the voltage amplifier. (b) The voltage amplifier with input signal source and load. Microelectronic Circuits, Sixth Edition

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Cascaded Amplifiers


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Table 1.1 The Four Amplifier Types (scan page 26)


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Figure 1.18 Determining the output resistance


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Frequency Response of Amplifiers

Figure 1.20 Measuring the frequency response of a linear amplifier: At the test frequency ω , the amplifier gain is characterized by its magnitude (Vo /Vi) and phase ø .


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T (ω ) =

V0 (ω ) Vi (ω )

T (s) =

V0 ( s ) Vi ( s )

L ⇒ sL


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s = jω C ⇒


1 sC

Single Time Constant Networks

Figure 1.22 Two examples of STC networks: (a) a low-pass network and (b) a high-pass network.


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Bode Plots

Figure 1.23 (a) Magnitude and (b) phase response of STC networks of the low-pass type. Microelectronic Circuits, Sixth Edition

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Figure 1.24 (a) Magnitude and (b) phase response of STC networks of the high-pass type. Microelectronic Circuits, Sixth Edition

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Classified of amplifiers based on frequency response

Figure 1.26 Frequency response for (a) a capacitively coupled amplifier, (b) a direct-coupled amplifier, and (c) a tuned or bandpass Sedra/Smith Copyright © 2010 by Oxford University Press, Inc. Microelectronic Circuits, Sixth Edition amplifier.

Figure 1.27 Use of a capacitor to couple amplifier stages.


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Microelectronics -Discrete Circuits

-Integrated Circuits


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