Definitions
RFIC (radio-frequency integrated circuit): RFICs are integrated circuits specifically designed for radio-frequency signal processing. RFIC design commonly uses lumped-circuit analysis, so designers focus on the overall circuit behavior rather than the distributed effects of individual elements. This simplifies design and integration, but at higher frequencies or in the microwave band distributed effects can become significant.
MMIC (monolithic microwave integrated circuit): MMICs are designed with distributed effects in mind. Signals in the microwave band have higher frequencies, so propagation within the circuit becomes more complex. MMIC design typically applies microwave circuit methods, accounting for transmission lines, matching networks, and other distributed parameters that affect circuit performance. This makes MMICs more suitable for high-frequency and microwave applications.
Frequency Perspective
RFIC: Typically covers the lower frequency range, approximately 10 MHz to 20 GHz. In this range, circuit design focuses on RF signal handling and transmission, and distributed effects are relatively small.
MMIC: Typically used at higher frequencies, roughly 20 GHz to 60 GHz and above. At these frequencies, the circuit design must more fully account for distributed effects, so microwave design techniques are required.
20 GHz to 60 GHz: This range sits between RFIC and MMIC. The appropriate design approach depends on the specific application and performance requirements; a given design in this band may be treated using either RFIC or MMIC methods.
Power
RFICs usually operate at relatively low power and are suitable for low-power, short-range communication applications. MMICs can handle higher power levels and are used in applications that require processing of high-power microwave signals, such as radar systems.
Design Considerations
RFIC design tends to follow traditional circuit design approaches and emphasizes the overall circuit function and connectivity. MMIC design requires more attention to microwave circuit characteristics, including transmission lines and matching networks, to meet high-frequency performance requirements.
Cost
Because RFICs generally operate at lower frequency ranges with lower power requirements, their manufacturing costs are typically lower than those of MMICs.
Applications
RFICs are commonly used in commercial and consumer applications such as communication devices and consumer electronics, for example NFC, Wi-Fi, and Bluetooth. MMICs are often used in military and specialized applications that require handling of high-frequency, high-power signals, such as radar.
Simulation Tools
MMIC design typically uses specialized microwave circuit simulation tools, such as ADS (Advanced Design System), to better account for distributed effects and microwave characteristics. Silicon-based MMIC workflows commonly rely on Cadence platforms; electromagnetic simulation may be performed with third-party tools such as SONNET. Passive structures can be simulated to obtain S-parameters, which are then imported into Spectre for combined simulation with active devices.
