Decoupling (electronics)
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electronics The field of electronics is a branch of physics and electrical engineering that deals with the emission, behaviour and effects of electrons using electronic devices. Electronics uses active devices to control electron flow by amplification ...
, decoupling is the prevention of undesired
coupling A coupling is a device used to connect two shafts together at their ends for the purpose of transmitting power. The primary purpose of couplings is to join two pieces of rotating equipment while permitting some degree of misalignment or end mov ...
between subsystems. A common example is connecting localized
decoupling capacitor A decoupling capacitor is a capacitor used to decouple one part of an electrical network (circuit) from another. Noise caused by other circuit elements is shunted through the capacitor, reducing its effect on the rest of the circuit. For hig ...
s close to the power leads of integrated circuits to suppress coupling via the
power supply A power supply is an electrical device that supplies electric power to an electrical load. The main purpose of a power supply is to convert electric current from a source to the correct voltage, current, and frequency to power the load. As a ...
connections. These act as a small localized energy reservoir that supply the circuit with current during transient, high current demand periods, preventing the voltage on the power supply rail from being pulled down by the momentary current load. Another common example of the use of
decoupling capacitor A decoupling capacitor is a capacitor used to decouple one part of an electrical network (circuit) from another. Noise caused by other circuit elements is shunted through the capacitor, reducing its effect on the rest of the circuit. For hig ...
s is across the emitter
bias Bias is a disproportionate weight ''in favor of'' or ''against'' an idea or thing, usually in a way that is closed-minded, prejudicial, or unfair. Biases can be innate or learned. People may develop biases for or against an individual, a group ...
resistor of transistor
common emitter In electronics, a common-emitter amplifier is one of three basic single-stage bipolar-junction-transistor (BJT) amplifier topologies, typically used as a voltage amplifier. It offers high current gain (typically 200), medium input resistance a ...
amplifiers to prevent the resistor absorbing a portion of the AC output power of the amplifier. Lossy ferrite beads may also be used to isolate or 'island' sections of circuitry. These add a high series impedance (in contrast to the low parallel impedance added by decoupling capacitors) to the power supply rails, preventing high-frequency currents being drawn from elsewhere in the system. Electronic circuits {{electronics-stub