RF MEMS Switches: Benefits, Selection, and Key Manufacturers

RF MEMS switches are known for their low power consumption and high isolation capabilities. Choosing the right switch involves considering factors like actuation voltage, reliability, and switching speed. RF switches see widespread use in RF design and RF test equipment across various sectors, including wireless infrastructure, test and measurement systems, medical equipment, defense, and aerospace.

Typical applications for these switches include switched filter banks, tunable filters, antenna tuning, RF front ends, switch matrices, and EM relays. RF switches can be broadly categorized into electro-mechanical and solid-state types.

MEMS stands for Microelectromechanical Systems. Solid-state switches utilize devices like PIN diodes, GaAs FETs, and silicon diodes in their construction.

What is an RF MEMS Switch?

RF MEMS switches are micromechanical switches designed to operate within the radio frequency (RF) range. They function similarly to a light switch, opening and closing a contact to allow or block signal transmission.

Due to their miniaturized mechanical components, RF MEMS switches are smaller in size and consume less power. The figure below illustrates the layout and block diagram of an RF MEMS Switch in an SP4T (Single-Pole, Four-Throw) configuration. Each of the four channels in this MEMS switch can be individually controlled by applying a gate voltage to its corresponding RF GATE pin.

The following specifications are typically considered when selecting an RF MEMS Switch:

• Operating frequency range
• Function of the switch (e.g., SP4T, SPST, DPDT)
• Insertion loss (in dB)
• IP3 (Third Order Intercept Point)
• On-State Resistance ($R_{ON}$)
• Off-State Capacitance ($C_{OFF}$)
• Isolation (in dB)
• Power (CW - Continuous Wave)
• Switching speed
• Lifetime (in number of cycles)
• Controller (Direct drive, serial to parallel, SPI, GPIO)
• Input voltage
• Packaging type (BGA, LGA, WL-CSP)

Benefits or Advantages of RF MEMS Switches

Here are the key advantages of using RF MEMS switches:

• Fast Switching Time: They offer quick switching speeds.
• Low Insertion Loss: They minimize signal loss during transmission.
• High Isolation: They provide excellent isolation between signal paths.
• High Power Handling: They can handle relatively high incident RF power.
• Small Size and Lightweight: They integrate mechanical and electrical components at a micro-scale, making them compact and lightweight. They are also cost-effective due to large-volume production capabilities.
• Low Power Consumption: They consume very little power.
• High ESD Immunity: They offer enhanced protection against electrostatic discharge.
• Robust Performance: RF MEMS switches deliver superior RF performance under extreme conditions, including harsh temperatures, vibration, shock, and RF power.
• Improved Robustness: RF MEMS switches are generally more robust compared to other switching technologies.

RF MEMS Switch Manufacturers or Vendors

The following table lists some prominent manufacturers and vendors of RF MEMS switches:

Conclusion

An efficient RF MEMS switch can significantly improve system performance. Choosing a high-quality switch from a reputable manufacturer is crucial for ensuring long-term reliability.