1P8T RF Switch 20-8000 MHz | 50S-2145

How do I choose a RF switch?

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When choosing a RF switch, you must first determine which type of switch best suits your application.  There are electro-mechanical switches and solid-state switches.  Both types of switches perform the same function (i.e. route RF signals), but each have key differences in RF performance.  Below we list a description of each type of RF switch and their differences for several important RF specifications.

Description:  Electro-mechanical RF Switches

Electro-mechanical switches use metal contacts that are physically moved inside the switch to route the RF signal through the switch.  Lifetime of mechanical switches is typically 1 million cycles.  Mechanical wear of the contacts will eventually cause a switch failure.  The RF path through a mechanical switch has no active components so the RF signal has very low distortion (i.e. -120dBc typical standard models).

For electro-mechanical switches there is a significant cost difference (i.e. 2 times or more) between models that are reflective and those that are absorptive (i.e. self-terminating).  The reflective models are lower cost.  An absorptive electro-mechanical switch has more internal parts to add the self-terminating functionality which results in a higher cost.

Description:  Solid-state RF Switches

Solid-state switches use active components (PIN diodes, FETs) to route the RF through the switch.  Because these active components are in the RF path, a solid-state switch will always have higher insertion loss than an electro-mechanical switch.  The advantage of the PIN diodes/FETs is their lifetime.  They have no mechanical wear and typical MTBF of 200,000 hours.  The disadvantage is that the active components cause more signal distortion than electro-mechanical switches.  A solid-state switch has a typical third order intercept point (IP3) of +45dBm.

Key RF Specifications:

Lifetime

Solid-state:  typical MTBF of 200,000 hours (always superior to electro-mechanical)
Mechanical:  1 million operations typical

Frequency Range

Solid-state:  Operate over a specific band (i.e. 20-6000MHz, 0.5-18GHz)
Mechanical:  Operate from DC to an upper limit (i.e. DC-18GHz, DC-40GHz)

Impedance

Solid-state:  50 Ohm or 75 Ohm
Mechanical:  50 Ohm or 75 Ohm

VSWR

Solid-state:  1P2T = 1.28:1 typical @ 4 GHz
Mechanical:  1P2T = 1.035:1 typical @ 4 GHz (typically superior to solid-state)

Insertion Loss

Solid-state:  1P2T = -1.7dB typical @ 4 GHz
Mechanical:  1P2T = -0.0445dB typical @ 4 GHz (always superior to solid-state)

Isolation

Solid-state:  1P2T = -66dB typical @ 4 GHz
Mechanical:  1P2T = -105dB typical @ 4 GHz (typically superior to solid-state)

Switching Speed

Solid-state:  nanoseconds or microseconds (always superior to electro-mechanical)
Mechanical:  milliseconds

Signal Distortion

Solid-state:  typical third order intercept point (IP3) of +45dBm
Mechanical:  typical PIM -120dBc for standard models (always superior to solid-state)

Control

Solid-state:  TTL or USB
Mechanical:  +12V, +15V, +24V, +28V, TTL, or GND activated

Cold Switch RF Input Power

Solid-state:  up to 1W for low power models and 250W for high power models
Mechanical:  in the order of 400W @ 200MHz, 90W @ 8GHz, 60W @ 18GHz

Hot Switch RF Input Power

Solid-state:  Can hot switch specified RF input power without causing damage to RF switch
Mechanical:  High power hot switching leads to arcing which damages the internal switch contacts

Available Models:

50 Ohm Models
75 Ohm Models