Why common mode choke is used in USB?

Actually, the main issue, and the reason you need a common-mode choke is due to the ability of a USB cable to radiate. if the signal enters your board, collides with a mismatch, the reflected signal will traverse the cable again, radiating.

What is a USB choke?

A common mode choke is an electrical filter that blocks high frequency noise common to two or more data or power lines while allowing the desired DC or low-frequency signal to pass.

What does common mode choke do?

Common mode choke coils are suited for noise suppression on lines with large current flows, such as AC/DC power supply lines. The distortion of the waveform is less. Common mode choke coils are suited for noise suppression on lines where signal waveform distortion causes a problem, such as video signal lines.

How do I choose a common mode choke for my power supply?

The main criteria for selecting a common mode choke are:

  1. Required impedance: How much attenuation of noise is needed?
  2. Required frequency range: Over what frequency bandwidth is the noise?
  3. ​Required current-handling: How much differential mode current must it handle?

What is power choke?

A power choke is connected between the mains supply and the inverter. It smoothes current peaks caused by the current consumption of the inverter. The waveform of the line current approaches back to the sinusoid. There is less circuit feedback.

Does common mode choke have polarity?

A choke might have a polarity so that the magnetic flux lines are in a certain direction relative to the chassis or some wires nearby. Also, the core might possibly be designed to react a certain way to the movement of flux in one direction or the other.

What does a ferrite choke do on a USB cable?

A ferrite bead (also known as a ferrite block, ferrite core, ferrite ring, EMI filter, or ferrite choke) is a type of choke that suppresses high-frequency electronic noise in electronic circuits.

What causes common mode noise?

The biggest source of common-mode noise is the difference in potential between two physically remote grounds. This is often the case when dealing with networked computer equipment where ground loops can occur. Typical effects of this can be intermittent reboots, lockups, and bad data transfer.

Can common mode noise?

Common mode noise is often referred to as common mode voltage (CMV) which is present at both input leads of an analog circuit with respect to analog ground. The biggest source of common-mode noise is the difference in potential between two physically remote grounds.

What does a choke do in a power supply?

In electronics, a choke is an inductor used to block higher-frequency alternating currents while passing direct current (DC) and lower-frequencies alternating current (AC) in an electrical circuit.

Where do you put the common mode choke?

Optimal placement

  1. starting from the antenna feed point for the conducted common mode component, and.
  2. starting from one quarter wavelength below the antenna feed point for the induced common mode component.