MMIC: Evolution and technology

An MMIC (Monolithic Microwave Integrated Circuit) is an integrated circuit that operates in the microwave frequency range (a few gigahertz) up to millimeter-wave frequencies (tens or hundreds of gigahertz). It is called “monolithic” because all active and passive components (transistors, resistors, capacitors, inductors, transmission lines, etc.) are fabricated on a single chip derived from the same semiconductor substrate. The concept of the MMIC emerged in the 1970s and 1980s, driven by a need for high performance—first for military applications (radar, microwave links, electronic warfare), and later for civilian telecommunications (satellites, microwave links, mobile phones, and Wi-Fi). Previously, microwave circuits were built using hybrid technology, meaning they consisted of discrete transistors and passive components mounted on a ceramic or alumina substrate. The main drawbacks of these hybrid assemblies were their bulk, cost, performance, and repeatability. MMICs have enabled significant miniaturization of microwave circuits, leading to new architectures (such as phase-scan antennas) and reduced production costs. RF performance has been improved through greater integration and a reduction in parasitic connection elements between the various components. Finally, MMICs benefit from the repeatability of microelectronic processes, which is far superior to that of hybrid circuits.

Terrestrial radio communications—whether for infrastructure (base stations and Wi-Fi routers) or mobile terminals—were the first market to require a significant volume of MMICs. This market is currently complemented by non-terrestrial communications, and more specifically by low Earth orbit (LEO) satellite constellations, which generate a significant volume of MMICs. Automotive driver-assistance radars are another example of a rapidly growing consumer application. Microwave integrated circuits are also used in imaging systems in the fields of healthcare, security, and industry. Originally, given the intended applications and associated performance requirements, MMICs were exclusively based on III-V technologies. They subsequently expanded to include silicon technologies, whose RF performance has increased dramatically over the past thirty years. Silicon-based MMICs, generally referred to as RFICs, now dominate the market because their performance is sufficient for a wide range of applications and they offer higher integration with an attractive cost-performance trade-off. In the first part, we present the state of the art and the frequency capabilities of MMICs, the main technological processes, and their application areas. We describe the main design steps and tools for MMICs. The second part is devoted to a general description of MMIC technology, followed by the specific steps for III-V and silicon technologies.

This study of...