While many systems use either analog or digital circuits, there are an increasing number of devices, components and pieces of equipment that used what is known as mixed signal design.
This is an integrated circuit using both digital and analog circuits within the same semiconductor. This allows the device to access both the digital and analog signals at the same time without the need to have two different circuits and systems within a single device. Often this includes the use of an analog to digital converter within the system.
While this may seem relatively simple, it is actually a very complicated issue. Analog circuits require very specific types of layouts, filtering and specific circuit design. Trying to integrate these with the more complex and less easily manipulated and visualized digital components can be very difficult and requires a high degree of expertise and experience.
Common Uses
There are many different uses and demands for mixed signal design in common use today. In general, any device that is using a chip, such as a cell phone, tablet or even a laptop, is going to be using a mixed signal chip or integrated circuit.
These types of systems are also used in audio equipment. The signal may come into a device, such as an MP3 player, as an analog signal through the tuner. Then, the analog signal passes through an analog to digital converter, which allows the digital amplifier in the system to be able to play the specific sound.
Considerations
When using both analog and digital components on a chip, it is important to be able to account for various types of differences. The analog and digital components on the chip, for example, may have different requirements for power. However, it would defeat the space-saving consideration of using these chips if they required two separate connections to the power source, so the design of the mixed signal chip has be very carefully constructed to accommodate these differences.
Additionally, digital signals tend to create more “noise” which can impact the effectiveness of the analog systems. Specialized noise buffering systems have to be carefully developed to prevent this type of interference within the chip itself.
The system-on-a-chip type of mixed signal design is used in many different applications besides just cell phones and sound and music systems. It is also used in routers, both local area networks and wide area networks, as well as for new types of radios used in private, commercial and military applications.