Mixed-signal Integrated Circuits
Mixed-signal integration refers to an integrated circuit design that combines both analog and digital circuitry on the same semiconductor die. Combining them in a single package results in highly-integrated, sophisticated functionality in both digital and analog devices.
Mixed-signal integrated circuits rely on data converters to function. Analog-to-digital converters, for instance, work to translate analog data streams into digital signals to allow digital devices to process them. They take in continuously varying input voltages and use binary numbers to approximate the output analog voltage.
Digital-to-analog converters, on the other hand, translate data signals from the digital realm to the analog realm. They accept inputs in the form of binary data and convert them to their corresponding analog signal outputs.
Mixed-signal integration plays a critical role in the making of essential components in FM tuners found in digital devices like media players with built-in digital amplifiers. With a basic analog-to-digital converter in a mixed-signal IC within the device, a sound wave, FM radio transmission, or any other analog signal can be digitized.
Some of the challenges of mixed-signal integration include:
- Analog inputs may receive noise from the quick-changing digital signals
- CMOS technology combines analog technology with digital technology at optimal performance, which will eventually replace mixed-signal ICs entirely
- Testing the functionality of mixed-signal ICs is often an expensive and complex undertaking and is usually a one-off task for implementation
- The design of analog circuitry cannot be automated to the level of a fully digital circuit design, even in mixed-signal ICs
- The design of these ICs requires high-level expertise since they are custom-made to offer very specific functionality
The most common examples of mixed-signal integrated circuits are digital radio chips, signal converters, delta-sigma modulation converters, and error detection and correction chips. Other applications include LAN and WAN routers, software radio, cellular phones, the control logic of a DVD player.