Physical System Hierarchy
Complex Electronic Systems
We're picking up our discussion here in section 1.3 where we're looking at physical system hierarchy. The first statement here is complex electronic systems are constructed using the basic building blocks used in simple systems. We had previously stated that all electronic systems are built from the same basic components. In this section, we're just going to look at the hierarchy, and we're going to look at six different building blocks used in electronic systems. We're going to start out with discrete components to printed circuit boards to integrated circuits for ICs to functional modules to entire systems on a chip, and this would be of the electronic type, and then entire systems on a chip of the electromechanical type.
First of all, let's look at initial building blocks. Here we have what we're going to refer to as discrete components. Here we see schematic diagrams for resistors, capacitors. Let's see, here's a capacitor here. Here is the resistor; diodes; MOSFETs, here we have one down in the corner; operational amplifiers; et cetera. We have a transistor up here. These and others are the building blocks of all electronic systems.
Printed Circuit Boards (PCBs)
The next item we'll look at it is printed circuit boards. Here we have a printed circuit board here on the right side of the screen. Components were mounted on a thin non-conductive boards. They are referred to as, and they have two common names, printed circuit boards, the acronym is PCB; or sometimes they're referred to as printed wiring assemblies, in that case, would be PWA.
Printed circuit boards, they utilize thin copper strips called traces. Sometimes they're referred to as runs. In this picture here you can see the copper lines here are actually the copper wires. We refer to these as runs. They are bonded to the non-conductive base material which the circuit board is mounted on. They provide electrical connections between components. The solder joints indicate components mounted on the other side. You see these little joints here, these are the connection point of components that are probably on the other side of this board.
PCBs may have multiple layers. The simple circuits often only use one side of the board. More complex circuits will use both sides and may have multiple layers. I don't know if you can see this clearly on this picture here, but you may see there are some faint copper-looking wires on this circuit board. These are indicating a layer below the one that you see here. Some may have as many as 20 layers, so circuit boards, especially with, for example, and computer system boards they may have many, many layers, sometimes as many as 20. Again, here is a picture of discrete components mounted on a circuit board. Here is another picture and here we see some capacitors here. We see some resistors, a little IC here looks like a diode. This looks like a variable potentiometer, and we have some capacitors here as well. Again, these are discrete components on a printed circuit board.
Then, we have integrated circuits, again, building blocks of complex electronic systems. As its name implies, many circuits are integrated together. This is usually done on a thin slice of silicon. Often, these are called a chip. They are very small, 0.5-0.2 inches wide. Millions of basic components can be etched on these tiny chips. They're functionally similar to their discrete components except they are many times smaller and they're connected by tiny traces of material like gold or aluminum. We'll continue here with IC. The same purpose is served as a printed circuit board except there is a profound reduction in the size. Over the time, if they produce a lot of them, there's also going to be a reduction in the cost. Oftentimes, over time, there're also often reduced failure rates as well. This has to do with being able to put all the chips on, or all of the components on a single piece of silicon. It usually stays around the same temperature the entire chip. That often results in reduced failure rates because often failure has to do with components that get overheated, they fail. When they're all on one single piece of silicon that chip usually stays at a uniform temperature and oftentimes will result in longer times without failures.
The manufacturing environments for ICs utilize high-quality clean rooms. Intel is an example. We have many students from NSC that go to work for Intel down in Portland. Once the chip is produced, it's mounted on larger packages such as those in your text shown on figure 1.11. Again, here is an example of integrated circuits. You can see these ICs soldered to a circuit board. Then, this is a higher resolution picture of an integrate circuit. This is actually a microprocessor. You'll notice this is what you typically see in a microprocessor. You don't see this portion that they have opened up in this particular photo. Notice the chip is very small. Remember, we said it was only from 0.2-0.5 inches in diameter. It is placed in a large case which provides for the pins for interface to a much larger system board. The actual chip is just this little tiny piece right here. You'll notice you can see this red portion here is actually all of the wires connecting to the tiny connections on the chip. Then, there are other wires that are going out to the many connection points. These are the many connection points that actually would connect to a system board or motherboard since this is a microprocessor.
The levels of integration in ICs, we have what we call here SSI for small scaled integration, then there is medium, large and very large. Then, over here to the right you can see the number of gates that if it's small scale integration one to ten, medium 11-99, large scale 100-999, and very large scale 1,000 to just under a million. That would be VLSI.
Then, functional modules. Electrical engineers combine integrated circuits and discrete components to build functional modules. These can be stand-alone items like an AM/FM radio or part of a larger system. The idea of functional modules is that you have a module that can be plugged into another system to give it greater functionality. Just one example I've mentioned here is the PCMCIA devices around examples of functional modules that interface with computers. In this particular situation, you have a computer that has a degree of functionality and the PCMCIA card can be plugged in and can give it greater functionality. There are all kinds of PCMCIA devices. They can be used for a network interface, global positioning, video capture and many others as well. But anyway, functional modules designed to... Well, sometimes they have functionality on their own, but typically they're designed to provide additional functionality to an existing system.
Systems on a Chip
Then, we have systems on a chip. We're going to be looking at two different types of... We're going to look at electronics systems on a chip and then electromechanical systems on a chip. Complete electronic systems are available on integrated circuits such as computers, calculators, and so on. ICs may combine many separate circuits on a single chip. Here we show a TI-86 calculator. The TI-86 calculator is a complete electronic system unto itself. Usually, they will have an IC built into them and all of the functionality is built into an IC, probably inside the box here, maybe about here, and you've got all the connections going to this particular IC, much like we saw in that integrated microprocessor chip. So we have a fully functioning unit that can do complex calculations and give us a video display as well. It is a stand alone system on a single chip.
Electromechanical Systems on a Chip
Then, we have electromechanical systems on a chip. Research is underway to provide for the integration of electronic and mechanical systems on a single silicon chip. Machines on these chips include notice valves, motors, levers, and gears. Manipulating these micro devices is possible at a molecular and even at the atomic level. This technology is referred to as nanotechnology. Over here to the right, we see a picture and this is a highly magnified nanomachine. You can see some gears doing something here. To get the perspective of the size here, this little creature here is actually a nano--or excuse me, a dust mite. These creatures are only about 250-300 microns in length. They are very small. Nanotechnology is a new science. It's in its infancy really. There are lots of things that are going to happen in nanotechnology. Here at North Seattle Community College we actually have a degree in nanotechnology. This particular course meets one of the requirements for that degree since many of these nanotechnology devices incorporate electronic components.
In summary, in section 1.3 we've looked at the hierarchy of electronics components and we went from the discrete components to printed circuit boards to integrated circuits for ICs to functional modules to complete electronic systems on a chip and to complete electromechanical systems on a chip.