Editing Mixed-signal integrated circuit (section)

==Overview {{anchor|Description}}==
[[Integrated circuit]]s (ICs) are generally classified as digital (e.g. a [[microprocessor]]) or analog (e.g. an [[operational amplifier]]). Mixed-signal ICs contain both digital and analog circuitry on the same chip, and sometimes [[embedded software]]. Mixed-signal ICs process both analog and digital signals together. For example, an [[analog-to-digital converter]] (ADC) is a typical mixed-signal circuit.

Mixed-signal ICs are often used to convert analog signals to digital signals so that digital devices can process them. For example, mixed-signal ICs are essential components for FM tuners in digital products such as media players, which have digital amplifiers. Any [[analog signal]] can be digitized using a very basic ADC, and the smallest and most energy efficient of these are mixed-signal ICs.

Mixed-signal ICs are more difficult to design and manufacture than analog-only or digital-only integrated circuits. For example, an efficient mixed-signal IC may have its digital and analog components share a common power supply. However, analog and digital components have very different power needs and consumption characteristics, which makes this a non-trivial goal in chip design.

Mixed-signal functionality involves both traditional active elements (like [[Transistor|transistors]]) and well-performing passive elements (like [[Inductor|coils]], [[Capacitor|capacitors]], and [[Resistor|resistors]]) on the same chip. This requires additional modelling understanding and options from manufacturing technologies. High voltage transistors might be needed in the power management functions on a chip with digital functionality, possibly with a low-power [[CMOS]] processor system. Some advanced mixed-signal technologies may enable combining analog sensor elements (like pressure sensors or imaging diodes) on the same chip with an ADC. 

Typically, mixed-signal ICs do not necessarily need the fastest digital performance. Instead, they need more mature models of active and passive elements for more accurate simulations and verification, such as for testability planning and reliability estimations. Therefore, mixed-signal circuits are typically realized with larger line widths than the highest speed and densest digital logic, and the implementation technologies can be two to four [[semiconductor device fabrication|generations]] behind the latest digital-only implementation technologies. Additionally, mixed signal processing may need passive elements like resistors, capacitors, and coils, which may require specialized metal, dielectric layers, or similar adaptations of standard fabrication processes. Because of these specific requirements, mixed-signal ICs and digital ICs can have different manufacturers (known as [[List of semiconductor fabrication plants|foundries]]).