What a DC block does
A DC block passes RF while stopping direct current. It is a series capacitor packaged as a connector or component, used to break DC paths between stages.
Why you need one
- Protects sensitive inputs from DC offset and bias voltages.
- Isolates test equipment from device bias.
- Prevents ground loops and bias conflicts between modules.
Key specs
- Frequency range and insertion loss.
- DC voltage rating.
- Return loss across the band — see how return loss sets the port-match requirement.
- Power handling.
Common applications
- Coupling RF between amplifiers and mixers.
- Protecting spectrum analyzers and power meters.
- Isolating antenna feeds from DC-powered LNAs, often alongside bias tees.
Selection tip
Pick a DC block whose voltage rating exceeds the highest DC level anywhere in the chain, with margin. Browse our DC blocks for board and connectorized use.