RF Choke / DC Block

An RF choke, also known as a DC block, is a passive electronic component used in driver amplifiers and RF circuits to prevent DC current from flowing while allowing RF signals to pass through. It typically consists of an inductor that presents high impedance at DC and low frequencies, but low impedance at RF frequencies, effectively blocking DC bias voltages from reaching sensitive RF components while maintaining signal integrity.

The RF choke operates on the principle of frequency-dependent impedance. At DC and low frequencies, the inductive reactance (XL = 2πfL) is low, allowing DC to pass, but when combined with a capacitor in series (forming the DC block), it creates high impedance at DC. At RF frequencies, the inductive reactance increases, allowing RF signals to pass with minimal attenuation while the capacitor provides low impedance path for RF signals.