EECE310_Chapter_8_Lecture_Notes__F05_

EECE310_Chapter_8_Lecture_Notes__F05_ - College of...

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Unformatted text preview: College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 8 Introduction to Electronics EECE 310 Preston D. Frazier, Ph.D., P.E., PMP College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 8 Introduction to Electronics Up until this point the focus has been on electrical circuitry. In this chapter the discussion shifts to electronic systems, in particular digital systems. EECE 310 Preston D. Frazier, Ph.D., P.E., PMP College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 8 Introduction to Electronics What is a signal? A signal is when either the voltage, v(t), or current, i(t), is varied over time in order to transmit information. One widely-used electronic component to increase the amplitude of a signal is an amplifier. An amplifier produces an output signal that is the identical wave shape of the input but has a larger magnitude. EECE 310 Preston D. Frazier, Ph.D., P.E., PMP College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 8 Introduction to Electronics The magnitude of an amplifier's voltage gain (AV) is defined as the ratio of the amplitude of the output voltage, v0, to the amplitude of the r r input voltage, vi. v0 V0 AV = The above definition holds true for the amplifier's current gain, AI. r i0 EECE 310 Preston D. Frazier, Ph.D., P.E., PMP AV = r vi Vi r I0 AI = r AI = ii Ii College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 8 Introduction to Electronics Most amplifiers are designed to operate at mid-band frequency region. Within this range the phase shift of device is either zero or 180 degrees. These angular values distinguish whether the amplifier is non-inverting ("positive") or inverting ("negative"), respectively. EECE 310 Preston D. Frazier, Ph.D., P.E., PMP College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 8 Introduction to Electronics Another important characteristic of an amplifier is its frequency response. No existing amplifier can amplify an input signal over an infinite range of frequencies. After reaching a particular high frequency, the amplifier will not longer be able to produce the same magnitude of the output signal as it did at previously lesser frequencies. This occurrence is called "roll off." EECE 310 Preston D. Frazier, Ph.D., P.E., PMP College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 8 Introduction to Electronics AC amplifiers exhibit roll off as the frequency is decreased below a certain low frequency value. The frequencies at which the voltage or current gain is reduced to 70.7% of its mid-band frequency are called the half-power frequencies (Chapter 7). The high frequency is deemed the upper or high-corner frequency (fHI). The low frequency is termed the low-corner frequency (fLO). EECE 310 Preston D. Frazier, Ph.D., P.E., PMP College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 8 Introduction to Electronics The difference in frequency between the high-corner and low-corner frequencies is called the bandwidth (BW) (i.e., BW = fHI - fLO). . BW may be measured in Hertz (f) or radians/second (). EECE 310 Preston D. Frazier, Ph.D., P.E., PMP College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 8 Introduction to Electronics Signals are used to transmit information. Therefore, a process is needed to attach the communication to the signal. The technique used is called modulation. Modulation is the process employed to encode information on an analog signal. EECE 310 Preston D. Frazier, Ph.D., P.E., PMP College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 8 Introduction to Electronics Modulation occurs in three forms: Amplitude Modulation (AM) Frequency Modulation (FM) Phase Modulation (PM) EECE 310 Preston D. Frazier, Ph.D., P.E., PMP College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 8 Introduction to Electronics Electronics involves the use of devices and circuits which specifically control the flow of electric current (i) to achieve a some pre-determined purpose. Electronic networks often contain electrical elements, for example resistors, inductors, and capacitors. They also contain electronic (solid state) devices, such as transistors and diodes. EECE 310 Preston D. Frazier, Ph.D., P.E., PMP College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 8 Introduction to Electronics The systems mentioned in the previous chapter (i.e., filters) process sinusoidal signals. Sinusoidal signals are continuous processes and are also known as analog signals. Electronic networks can operate utilizing discrete functions which are otherwise called digital signals. EECE 310 Preston D. Frazier, Ph.D., P.E., PMP College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 8 Introduction to Electronics Analog Signal: Digital Signal: EECE 310 Preston D. Frazier, Ph.D., P.E., PMP College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 8 Introduction to Electronics A digital signal has a restricted range of allowable amplitudes, and each magnitude in any given range has the same significance. Binary signals are the preferably used digital signals and have only two (2) ranges, either "0" or "1." The values of "0" and "1" are called logic values. EECE 310 Preston D. Frazier, Ph.D., P.E., PMP College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 8 Introduction to Electronics A "0" or "1" is a single binary digit and called a bit. A bit represents a very small amount of information. Bits are used to quantizing information. To quantify a binary signal to encode a large amount of information it is necessary to use resolution zones. The number of resolution zones (Z) needed to encode information is directly correlated to the n number of bits (n). EECE 310 Preston D. Frazier, Ph.D., P.E., PMP Z =2 College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 8 Introduction to Electronics The first bit in a binary signal is often designated the most significant bit (MSB). The last (or final) bit in a binary signal is usually assigned as the least significant bit (LSB). An eight-bit segment is equivalent to 1 byte. Four (4) bits are known as a nibble. EECE 310 Preston D. Frazier, Ph.D., P.E., PMP College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 8 Introduction to Electronics Information represented as zeros and ones in a signal for a digital system is processed mainly by elements called logic gates. There are five principal gates (along with their respective truth tables) that need to be studied: NOT gate (inverter) NOR gate NAND gate OR gate AND gate EECE 310 Preston D. Frazier, Ph.D., P.E., PMP College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 8 Introduction to Electronics NOT gate (inverter): I = I Truth Table: 0 NOT 1 1 0 EECE 310 Preston D. Frazier, Ph.D., P.E., PMP College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 8 Introduction to Electronics Truth Table: I1 0 0 1 1 OR gate: I1 + I2 = O I2 0 1 0 1 EECE 310 Preston D. Frazier, Ph.D., P.E., PMP O (Output) 0 1 1 1 OR2 College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 8 Introduction to Electronics Truth Table: I1 0 0 1 1 AND gate: I1 I2 = O I2 0 1 0 1 EECE 310 Preston D. Frazier, Ph.D., P.E., PMP O (Output) 0 AND2 0 0 1 College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Truth Table: Chapter 8 Introduction to Electronics NOR gate: I1 + I2 + I3 = O I1 0 0 0 0 1 1 1 1 I2 0 0 1 1 0 0 1 1 I3 0 1 0 1 0 1 0 1 O (Output) 1 0 0 0 0 0 0 0 NOR3 EECE 310 Preston D. Frazier, Ph.D., P.E., PMP College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 8 Introduction to Electronics Truth Table: I1 0 0 0 0 1 1 1 1 I2 0 0 1 1 0 0 1 1 I3 0 1 0 1 0 1 0 1 O (Output) NAND gate: I1 I2 I3 = O 1 1 1 1 1 1 1 0 NAND3 EECE 310 Preston D. Frazier, Ph.D., P.E., PMP College of Engineering, Architecture, and Computer Sciences Department of Electrical and Computer Engineering Chapter 8 Introduction to Electronics Important Note about Truth Tables for Digital Logic Gates: The truth table is a chart showcasing the logic state of the output for every possible input combination. The MSB is always the first input (the farthest to the left) of the inputs in the truth table. The LSB is always the last input of the inputs (closest to the right) in the truth table. EECE 310 Preston D. Frazier, Ph.D., P.E., PMP ...
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This note was uploaded on 10/15/2008 for the course EECE 310 taught by Professor Frazier during the Fall '08 term at Howard.

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