Transitions in Digital Step Attenuators (DSA): Glitch-Free, Safe-State, No-Protection

Q.

What are the differences between glitch free, safe state and no protection transitions in digital step attenuators (DSA)?

A.

Digital Step Attenuators usually have an array of attenuator stages internally and turning on or off the different stages determines the state of the attenuator. Additional timing circuitries may be implemented in design to control the transient behavior of the attenuator when changing states.

DSAs are designed and offered with various transition performances:

• With no glitch protection – attenuators may have overshoot and/or undershoot when changing attenuation states.
• With glitch free transitions – attenuators directly go to the desired attenuation state with minimal overshoot and/or undershoot.
• With safe-state transitions – attenuators switch to the maximum attenuation state before settling to the desired attenuation state.

Typically, the glitch free or the safe transition design have slower switching response time compared to the no protection designs. To be able to compare the switching transients quantitatively, we include the glitch performance in the Electrical Specifications Table as Overshoot/Undershot our newer product datasheets.

Below is a summary of key digital step attenuators:

*Please note: The lower frequency cutoff for some of the legacy Hittite products are incorrectly stated. These products cannot be operated at true DC frequencies. We are actively working on converting these datasheets to ADI-format and are updating the lower cutoff frequencies.