Class Format 6 Some presentations by myself Q& A in class Quick questions in class to be answered
Topics to be Covered next few Lectures 7 That electronic circuits process signals, and thus understanding electrical signals is essential The Thevenin and Norton representations of signal sources. The representation of a signal as the sum of sine waves. The analog and digital representations of a signal. The most basic and pervasive signal-processing function: signal amplification, and correspondingly, the signal amplifier. How amplifiers are characterized (modeled) as circuit building blocks independent of their internal circuitry. How the frequency response of an amplifier is measured, and how it is calculated, especially in the simple but common case of a single-time constant (STC) type response.
Introduction integrated-circuit (IC) technology. Microelectronics refers to the integrated-circuit (IC) technology. Contains hundreds of millions of components in a small piece of silicon (known as a silicon chip) whose area is on the order of 100 mm 2.
Introduction complete digital computer, a microcomputer One such microelectronic circuit is a complete digital computer, which accordingly is known as a microcomputer or, more generally, a microprocessor. We shall study electronic devices that can be used singly (in the design of discrete circuits) or as components of an integrated-circuit (IC) chip. design and analysis interconnections We shall study the design and analysis of interconnections of these devices. We shall also learn about available IC chips and their application in the design of electronic systems.
Introduction Today we will learn about signals and about one of the most important signal-processing functions electronic circuits are designed to perform, namely, signal amplification.
Signals Signals contain information about things and activities around us in the physical world. Information about the weather including temperature, humidity, wind speed, etc. The voice of radio announcer in the microphone is a signal.
Signals processing To extract required information from a set “signals”, there are some “processing”. processing“electronic systems”. Usually the processing done by “electronic systems”. electrical signals, voltage or current To do so, the signal must be first converted to electrical signals, voltage or current. transducers This conversion is done by “transducers “
Transducers A variety of transducers exist. Each type of suitable for special type of physical signal. Sound wave microphone Sound wave generated by human is converted into electrical signals using microphone.
Transducers are not interested We are not interested in transducers by themselves. We will assume that the signals are already exist in a form of voltage or current.
Thevenin Form The signal is represented by V s (t) Source resistance R s
Norton Form The signal is represented by current source i s (t) Source resistance R s
Source Resistance R s in Thevenin preferred to be low R s in Notron preferred to be High
Signals and Time The signal can be represented by Time- Varying quantity as follows:
Frequency Spectrum of Signals An extremely useful characterization of a Signal, and for that matter of any arbitrary function of time, IS In terms of its frequency spectrum. Such a description of signals is obtained through the mathematical tools of Fourier series and Fourier transform. Suffice it to say that they provide the means for representing a voltage signal V s (t) or a current signal i s (t) as the sum of sine-wave signals of different frequencies and amplitudes.
Frequency Spectrum of Signals This makes the sine wave a very important signal in the analyses, design, and testing of electronic circuits
If we use N binary digits (bits) to represent each sample of the analog signal. then the digitized sample value can be expressed as b 0 is the Least Significant Bit (LSB) b N-1 is the Most Significant Bit (MSB)
Analog to- digital converter ( A/D or ADC) increasing the number of bits reduces the quantization error and increases the resolution of the analog-to-digital conversion. however, usually mobtained at the expense of more complex and hence more costly circuit implementations