CHAPTER 1 THE REVOLUTIONARY FIELD OF ELECTRONICS N elevision stereophonic recording and playback the computer robots and space probes are all products of elec tronics Electronics is the branch of physics concerned with the generation and behavior of electrons as in transistors and electron tubes It is especially concerned with their use in electronic devices in which electricity is used to control communicate and process infor mation These devices have caused greater changes in everyday life than those of any other technology introduced in the 20th century THE ELECTRONIC SIGNAL The basis of electronics is the electronic signal an electric current that represents information There are two basic types of electrical signals analog and digital In analog signals some continuously variable aspect of IO
THE REVOLUTIONARY FIELD OF ELECTRONICs the electrical current represents the infor mation In amplitude modulated AM radio transmissions for example the amplitude or strength of the electromagnetic radio wave is proportional to the amplitude of the signal the volume of the sound that the radio wave carries The greater the ampli tude of the radio wave the louder the sound that radiates from the radio speaker In contrast digital signals use standard ized pulses to represent numbers With a digital audio signal the amplitude of the 271 The iPad2 is a touch screen device that is smaller than a laptop com puter but larger than a smartphone Justin Sullivan Getty Images ITTHL II TTI HUI
ELECTRONICs signal for a set amount of time is converted to a number represented by for example 16 pulses of fixed duration and amplitude The audio signal as a whole is transmitted as a series of such 16 pulse codes Most electronic devices use digital sig nals In these signals the numbers are almost always represented in binary code that is instead of using a number system based on 10 as is used in writing numbers and manual arithmetic electronic systems use numbers based on 2 There are only two basic numbers in this system 0 and 1 with 1 being repre sented by a pulse and o by the absence of a pulse or some similar arrangement A digital computer for example can rec ognize only two states in each of its millions of circuit switches on or off or high voltage or low voltage By assigning binary numbers to these states such as I for on and o for off and linking many switches together a computer can represent any type of data from numbers to letters to musical notes This process is called digitization SEMICONDUCTING DEVICES Electronic devices that manipulate digital and analog signals today are predominantly 12
THE REVOLUTIONARY FIELD OF ELECTRONICs In In the Semiconductor wafer Semiconductors are instrumental in operating a digital and analog signals Bloomberg via Getty Images 13 TTI HUI
