The Combination of Art and Science of RF and Mixed-signal Design

Over the past couple of years, mixed-signal integrated circuit (IC) design has been one of the most technically tough and interesting segments of the semiconductor industry. Regardless of every advancement that has taken place in the semiconductor industry over that time period, the one continuous requirement is still to ensure the analog world we reside in connects effortlessly with the digital world of computing, a requirement particularly driven by the existing prevalent mobile environment and swiftly emerging Internet of Things (IoT) “re-evolution”.

Digital and memory ICs comprise about two-thirds of today’s approximately $320 billion worldwide semiconductor market. These ICs are driven by Moore’s Law and advanced CMOS process technology, which lowers the cost and enhances the integration of semiconductor devices annually. Discrete and analog semiconductors represent about one-fifth of the global semiconductor market and are mostly served by older semiconductor process technologies as core analog parts are costly to manufacture in newer process nodes.

Mixed-signal ICs account for about one-tenth of the global semiconductor market. This approximation relies on how you count a mixed-signal IC, which could be specified as a semiconductor tool that integrates considerable analog and digital functionality to provide an interface to the analog world. Archetype of mixed-signal ICs consist of system-on-chip (SoC) devices; cellular, Wi-Fi, Bluetooth as well as wireless personal area network (WPAN) transceivers; GPS, TV, and AM/FM receivers; audio as well as video converters; advanced clock and oscillator devices; networking interfaces; and recently, low-rate WPAN (LR-WPAN) wireless MCUs. Extremely integrated mixed-signal IC solutions often supersede legacy technologies in well-known semiconductor markets when the required functionality and analog efficiency could be accomplished at reduced expense compared to other or discrete analog approaches. The more crucial part is, a high level of mixed-signal integration significantly streamlines the engineering required by system manufacturers, allowing them to concentrate on their core applications and reach market much faster.

Designing Mixed-signal ICs

Mixed-signal ICs are hard to design and manufacture, specifically if they consist of RF capability. A huge standalone analog and discrete IC market exist since analog integration with digital ICs is not an easy, simple process. Analog and RF design has frequently been referred as a “black art” due to the fact that a lot of it is done usually by experimentation and very often by intuition. The contemporary mixed-signal design must always be considered about a lot more science than alchemy. “Brute force” analog integration must constantly be avoided, as experimentation is a really costly process in IC development.

The real “art” in mixed-signal design need to result from a deep understanding of how the underlying physical interaction phenomena manifest in facility systems integrated with a robust and elegant design methodology based on a digital-centric method. The perfect strategy combines mixed-signal design and digital signal processing and allows the integration of complicated, high-performance as well as very delicate analog as well as digital circuits without the anticipated trade-offs. The effective capacities of digital processing in fine-line digital CMOS procedures could be utilized to make up and adjust for analog blemishes and alleviate undesirable interactions, hence boosting the speed, accuracy, power usage, and eventually the cost and usability of the mixed-signal tool.

Moore’s Law has been incredibly consistent with digital circuit design, increasing the variety of transistors in a provided area every 2 years, and it is still partly appropriate in the age of deep sub-micron technologies. This regulation does not usually apply as well to analog circuits, resulting in a considerable lag in the fostering of scaled technologies for analog ICs. It is not unusual for analog devices to be still designed as well as manufactured 180 nm technologies and above. The fact is that the scaling of the process technology partly drives the area and power scaling in analog circuits and often comes to be a design barrier. In fact, analog scaling is more frequently driven by the reduction of undesirable effects (such as analytical tool mismatch or noise resulting from flaws at materials interfaces), which is the outcome of quality enhancements of the process itself. Consequently, mixed-signal designers choose to rely upon processes that are the couple of steps behind the cutting edge of process technology, which could still enhance device quality by depending on a few of the most recent technological advancements. To put it simply, the analog facets of Moore’s Law fall back the standard digital approach. The scenario is a lot more dynamic, as well as the digital/analog technology void, could be partly made up if it is still worth the investment of the IC modern technology suppliers.

An ideal manufacturing process node for mixed-signal IC design lags behind the bleeding side of process technology, and the option of nodes is a compromise of a number of factors, which inevitably relies on the quantity of analog and mixed-signal circuitry consisted of in the device. More specifically, a more digital-centric mixed-signal design method allows the designer to utilize advanced process nodes in order to fix one of the toughest commercial issues with analog circuit integration– the capability to integrate analog to decrease expenses while increasing functionality. Design engineering teams at numerous leading semiconductor firms are proactively pushing the limits of mixed-signal design and attempting to address this challenge with unique solutions where logic gates and switching components are changing amplifying and large passive devices.

The IoT and Mixed-signal Design

The Internet of Things aggregates networks of IoT nodes, i.e., extremely low-priced, intelligent and connected sensors and actuators utilized for data collection and tracking in myriad applications that enhance energy efficiency, security, healthcare, environmental monitoring, industrial process controls, transportation, and livability in generally. IoT nodes are forecasted to reach 50 billion devices by 2020, and perhaps getting to the one trillion thresholds just a couple of years later on. These astronomical market numbers pose significant restrictions in regard to engineering, manufacturability, energy consumption, maintenance, and eventually the health of our environment. Along with being offered in astonishingly high quantities, all these IoT nodes need to be really small, energy efficient, and secure, and they are normally not easily accessible to customers for maintenance. IoT nodes frequently require to run with extremely small coin cell batteries for years or even more, or perhaps counting on energy scavenging strategies.

These application needs make the IoT node the utmost prospect for extremely innovative digital-centric mixed-signal design methods. The optimal IoT node will need modern mixed-signal circuits to interface to actuators and sensors. They need to consist of RF connectivity, usage really power-efficient wireless protocols and need marginal external elements. They likewise need to consist of power converters to optimize power efficiency and manage various battery chemistries or energy sources, all characteristics generally accessible with mature process nodes. At the same time, these IoT nodes will require for reasonably complicated, ultra-low-power computing resources and memories to store and execute applications and network protocol software, which is much better addressed with finer technologies. The present instantiation of such a paradigm is a mixed-signal IC that is commonly known as a wireless MCU: an easy-to-use, small-footprint, energy-efficient, and highly integrated connected computing device with sensing and actuating capabilities.

The spreading of ultra-low-power wireless MCUs is crucial to the innovation of the IoT. Wireless MCUs supply the minds, sensing, and connectivity for IoT nodes, from wireless security sensors to digital lighting controls. The combination of art as well as science for mixed-signal design is the vital enabler for the growth of next-generation wireless MCUs that link the analog, RF, as well as digital worlds and maximal advantage of the power of Moore’s Law, without concessions in efficiency, cost, power consumption, or size.