RF Switches for test and measurement | RF switch vendors

This page describes basics of RF switches used for test and measurement. It mentions specifications and types of RF switches including popular vendors or manufacturers. This will help one make right selection for the RF switches for their need.

Technical specifications of RF switch

Following table mentions technical specifications of an RF Switch:

RF Switch specification Description
Frequency range OR bandwidth Range of frequencies (i.e. Bandwidth) over which RF Switch is useful.
Characteristic impedance 50 Ohm or 75 Ohm
Insertion loss Power loss or voltage attenuation caused by RF Switch on signal at operating frequency.
Return Loss/VSWR VSWR is used to determine ratio of reflected wave to transmitted wave. This value determines how much power will be reflected and how much will be transmitted when switch is coupled with the transmission line or with other devices in the setup.
VSWR = (1+RL)/(1-RL), RL (dB) = 10* Log(PReflected/PIn)
Isolation and Crosstalk Isolation is defined as magnitude of signal which gets coupled across open circuit.
Crosstalk is defined as magnitude of signal which is coupled between circuits.
Topology There are two types of topologies exist in RF viz. multiplexers and SPDT (Single Pole Double Throw) relays. Based on this appropriate RF switch is selected for design/application.
Rise Time It is the specification of RF switch which should be less than rise time of highest harmonic. This harmonic need to be routed with minimal of distortion through the RF Switch.

Types of RF switches

Following are the types of RF switches and their comparison specifications. This guide will help one select the right type of RF switch as per desired specifications based on application of use.

PIN Diode RF Switch

This type of RF switches made of PIN diodes have following features:
• Frequency range: from MHz
• Insertion loss: medium (Roll off at low frequencies)
• Isolation: Good at high frequencies
• Switching speed: Fast
• Power consumption: High

FET based RF Switch

This type of RF switches made of FET solid state devices have following features:
• Frequency range: from DC
• Insertion loss: High (Roll off at high frequencies)
• Isolation: Good at low frequencies
• Switching speed: Average
• Power consumption: Low

Hybrid RF Switch

Hybrid switches are made using FET and PIN diodes. This type of Hybrid RF switches has following features:
• Frequency range: from KHz
• Insertion loss: High (Roll off at high frequencies)
• Isolation: Good at high frequencies
• Switching speed: Average
• Power consumption: Moderate

RF Switches have either of the following topology architectures.
1. Multiplexer based: This design routes numerous inputs sequentially to the one output or vice versa. RF multiplexers are made using multiple SPDT relays.
2. SPDT (Single Pole Double Throw): This design can route two inputs to one output port or vice versa.

RF switch vendors or manufacturers

Following are the popular vendors of RF Switch.
• Peregrine Semiconductor
• Analog Devices
• Pasternack
• Mini Circuits
• Infineon
• Skyworks
• National Instruments
• Rohde & Schwarz
• Keysight Technologies

RF test and measurement equipments

RF Vector Signal Generator
Keysight vs Tektronix vs Rigol Spectrum Analyzers
Waveguide Mixer
Sound Level Meter
PIM Analyzer
Noise Figure Meter
Near Field Probe Set