DC block

Not to be confused with Feedthrough capacitor.

DC block

Component type	Passive
Working principle‍	Direct Current
Electronic symbol

DC blocks are coaxial components that prevent the flow of audio and direct current (DC) frequencies while offering minimum interference to RF signals. There are three basic forms of DC blocks. "Inner only" models have a capacitor in series with the center conductor, "outer only" models have a capacitor in series with the outer conductor, and "inner/outer" models have capacitors in series with both the inner and outer conductors. The insulation material on the outer models is non-conductive. Applications include ground loop elimination, signal source modulation leakage suppression, system signal-to-noise ratio improvement, test setup isolation and other situations where undesired DC or audio current flows in the system.

DC blocks serve a wide range of practical functions, primarily in systems where undesired DC or audio currents can degrade performance. One of their key applications is in eliminating ground loops, which are common sources of hum and noise in audio and video systems. DC blocks also help suppress signal leakage, such as modulation leakage in signal sources, thereby improving the system’s signal integrity. They can enhance the signal-to-noise ratio (SNR) in sensitive communication systems by preventing the intrusion of unwanted currents. Additionally, DC blocks are used in test setups to isolate different parts of the system and prevent interference, ensuring more accurate measurements and maintaining the quality of the overall signal transmission.

See also

• Bias tee
• Choke (electronics)
• DC-blocking capacitor

External links

• What Is a DC Block? // wiseGEEK
• DC Blocks & Bias Tees