Meaning
High-frequency electronic switches designed to route radio-frequency signals operating at frequencies below one gigahertz. These devices are used in wireless systems to select between different antenna paths. In these applications, sub-gigahertz rf switches must exhibit low insertion loss and high isolation to prevent signal degradation.
Electrical Performance
Evaluation of performance depends on the insertion loss in the on-state and the signal isolation in the off-state. Minimizing the on-resistance of the switch reduces the loss of signal power, which is necessary to maintain high receiver sensitivity and transmitter efficiency. High isolation prevents the unwanted leakage of signals between adjacent channels, ensuring that the selected signal path remains free from interference.
Device Integration
Implementing these switches in modern smart devices requires the integration of the switching elements with control circuitry on a single silicon or gallium-on-insulator die. This integration reduces the overall footprint and simplifies the design of the radio-frequency front-end module. The choice of packaging also plays a critical role, as parasitic capacitances and inductances from the package can degrade the high-frequency performance and limit the isolation that can be achieved.
Co-designing the package with the semiconductor die allows for the optimization of the impedance match, minimizing signal reflections at the input and output ports.
Power Handling
When operating under high transmit powers, the switch must withstand significant voltage swings without introducing harmonic distortion or undergoing dielectric breakdown. Utilizing materials with high breakdown voltages, such as silicon-on-insulator or gallium nitride, enables the device to handle high power levels while maintaining low distortion. This high linearity is necessary to meet the stringent emission masks of modern communication standards.
