Failsafe Devices

A failsafe device is an active RF part designed to default to a useful state — usually a low-loss bypass path — when its supply voltage is lost. In a normally-on amplifier or attenuator, total power loss makes the part appear as a high-impedance break in the signal chain, killing the system. A failsafe part instead presents a passive through-connection so signals can continue to flow (and downstream stages can be polled, status can be reported, or the radio can fall back to a low-power mode) until power is restored.

Failsafe behavior is essential in tower-mounted amplifiers, distributed antenna systems, satellite ground terminals, and any high-reliability radio where the cost of a stuck signal path is much higher than the cost of an extra dB of NF or insertion loss. The trade-off is a small linearity / noise penalty from the integrated bypass switching circuitry compared to a non-failsafe amplifier of the same family.

Selection comes down to the same parameters you'd evaluate for the underlying amplifier or attenuator type, plus the failsafe transition behavior — how cleanly does the part switch to bypass when V_DD collapses, and how quickly does it return to amplification when power is restored. Most parts spec the bypass insertion loss with no power applied.

The table below lists the active failsafe portfolio sorted by SKU. Click any SKU for the full data sheet, S-parameters, and reference designs.