An electrical circuit in a device or system, whether for power, control, sensing or whatever, can simply be made from discrete electronic components wired together on a circuit board. As the sophistication of the system grows, however, the size of the board and the number of discrete components on it can get too large, too expensive, or too inefficient.
Enter the integrated circuit (IC). An integrated circuit is simply the integration of the functions of multiple discrete components and their connections on a single tiny chip. The chip is typically made of silicon and, through miniaturization, can hold massive amounts of transistors, capacitors and resistors that can be used to perform calculations, store data, or control devices. And while the idea is simple, the execution of it is anything but.
Developed in the 1950’s after the advent of the transistor, the IC was largely the result of the need for computing power to be supplied by smaller and more efficient systems. Say goodbye to the vacuum tube! With continuing innovation and huge investments, ICs have gotten progressively smaller and more complicated over the past 70 years. Current editions can integrate literally millions of components on a single chip the size of your fingernail. The development of ICs has also been a progression of denser and denser integration coupled with greater and greater computing power along with concurrent development of sophisticated software tools for the design and testing of the chips themselves.
Three basic types of ICs exist today, categorized by their design or how they work:
- Analog (or Linear) - designed to process analog signals that can vary, as in changes in frequency, voltage, or current. Analog IC output can vary depending on the input. Typically used in audio and RF applications. Examples include sensors, amplifiers, oscillators and voltage regulators.
- Digital - designed to function at defined levels of input signals, which must be one of two discrete levels. Digital ICs contain logic gates which are binary in nature (using ones and zeros). Usually found in computers, networking equipment, and consumer electronics. Examples include memory, interface and logic chips and shift registers.
- Mixed Signal - contain both analog and digital circuits, so analog and digital signals can be processed simultaneously. Examples include A/D and D/A converters, clock & timing chips, data acquisition chips and tuners.
Since integrated circuits are literally the miniaturization of larger circuits, their functions can be virtually limitless. Several broad IC functions can be categorized, however, including:
- Memory: RAM, ROM, EPROM
- Processing: microprocessors, microcontrollers, gate arrays
- Commodity: op-amps, oscillators, tuners
- Semi and full custom: application specific ICs (ASICs), systems on a chip
The level of sophistication of the ICs that might be used in your end product is dependent on the complexity of the system you are producing. Off-the-shelf ICs, like amplifiers, power regulators or op-amps can be used to reduce the discrete component count in your circuit, decrease power usage, and save manufacturing and testing costs.
More complex products may require the use of IC microcontrollers or microprocessors to give you the functionality and processing power that you need. Cost savings again come from reduction in component count and manufacturing simplicity, along with the ability to add even more sophisticated features to your product.
At the highest end, full-custom ICs exclusive to your design and including all of your circuit components can be produced. This requires extensive upfront design work and considerable cost since the economies of mass production are not usually present. If your production runs are high, however, and your need for function and exclusivity are relevant, then this may be an option.
Designing a system that includes IC’s demands upfront planning and knowledge of your product end-use. As in the selection of discrete components, sourcing IC’s brings up the usual questions of cost, availability, specifications, etc. Some additional factors that may need to be considered include:
- System electrical demands and characteristics
- Optimum package style (DIP, SIP)
- Package size (footprint on circuit board)
- Environmental requirements (temperature, vibration, moisture)
- Lifecycle demands
- Maintenance or repair considerations
- Testing requirements
Throughout their 70+ years of development, ICs have been driven by the demands of smaller size, greater function and less cost. Today’s IC designs are in everything from consumer and industrial products to military weapons systems. Modern automobiles typically contain over 3,500 individual ICs and rely on them for a level of driving, entertainment and safety sophistication that was impossible just a few years ago.