MMICs

MMIC stands for Monolithic Microwave Integrated Circuit, a type of integrated circuit built to operate at microwave frequencies. In a MMIC, active devices such as transistors and passive components like resistors, capacitors, and transmission lines are fabricated on a single semiconductor substrate, enabling compact, repeatable high-frequency circuits. The operating frequency range generally spans from about 300 MHz to several hundred gigahertz, depending on the process.

Materials and devices: Common MMIC technologies use gallium arsenide (GaAs) MESFETs or HEMTs, indium phosphide (InP) HBTs or HEMTs, GaN HEMTs, and, more recently, silicon-germanium (SiGe) BiCMOS. Passive elements are formed as planar transmission lines (microstrip, coplanar waveguide, or stripline) and integrated lumped components on the same substrate. MMICs can include amplifiers, mixers, oscillators, phase shifters, switches, attenuators, detectors, and limiters.

Advantages over discrete hybrids include smaller size, better mechanical and optical reliability, easier mass production, and potentially lower cost at high volumes, along with improved repeatability and integration with other RF circuitry. Limitations involve fabrication complexity, yield control at very high frequencies, heat dissipation, and interconnect losses that can limit high-frequency performance.

Applications span wireless and satellite communications, radar and defense, instrumentation, and test equipment. Typical metrics include gain, noise figure, input/output return loss, output third-order intercept point (IP3), P1dB, and bandwidth. Ongoing trends emphasize higher power efficiency, operation at mmWave frequencies, and the use of GaN and SiGe BiCMOS processes to extend performance and integration.