MMIC
Understanding MMICs
MMICs have transformed the RF industry by replacing complex multi-component assemblies with single-chip solutions. A function that previously required a circuit board with dozens of discrete components can now be implemented on a chip measuring 1-5 mm per side. This reduces size, weight, assembly cost, and unit-to-unit variation.
MMIC Technologies
- GaAs pHEMT: Dominant for LNAs, switches, and small-signal MMICs to 100 GHz.
- GaN HEMT: High-power MMICs for PAs and T/R modules. 5-10x power density of GaAs.
- InP HEMT: Best noise and gain above 40 GHz. Used in radio astronomy and millimeter-wave receivers.
- SiGe BiCMOS: Lower cost, high integration level. Suitable for commercial 5G and automotive radar.
Common MMIC Functions
- LNA: Low-noise amplifier, single or multi-stage.
- PA: Power amplifier, from milliwatts to tens of watts.
- Mixer: Frequency conversion, single or double balanced.
- Switch: SPDT, SP4T, transfer switches for signal routing.
- Multifunction: Complete receiver front-ends, T/R modules, or frequency converters on a single chip.
Frequently Asked Questions
What is an MMIC?
An MMIC is a complete microwave circuit fabricated on a single semiconductor chip. It integrates transistors, resistors, capacitors, inductors, and transmission lines to implement functions like amplification, mixing, switching, and frequency conversion in a compact, reproducible form factor.
What semiconductor is used for MMICs?
The most common MMIC substrates are GaAs (for low-noise and general purpose), GaN (for high power), InP (for highest frequency and lowest noise), and SiGe (for cost-sensitive commercial applications). The choice depends on the required frequency, power, and noise performance.
What frequency range do MMICs cover?
MMICs are available from DC to beyond 300 GHz. GaAs and GaN MMICs typically cover DC to 100 GHz. InP MMICs extend to 300+ GHz. SiGe MMICs are practical to about 100 GHz. The available frequency range depends on the transistor technology and process node.