Why does switching power supply cause RF interference?

This higher frequency of operation is also the reason why switching power supplies often cause interference issues to radio receivers: It is the harmonics from this high-power oscillator that are more likely to be conducted to the outside world via the AC power connector and/or the DC output.

How is RF energy forced to be equal?

To force the RF energy to be equal is the job of the two capacitors shown – one on the input, and the other on the output. This particular power supply had only a capacitor on the load side of the power supply – where the noise was being generated.

Are there any problems with RFI switching supplies?

Stepping back off the soapbox, these switching supplies – even if well-built and long-lasting (if you are lucky enough to encounter one) bring us to the second of the two problems concerning us about these devices: The generation of RFI, or R adio F requency I nterference.

Why does a bifilar choke cause RF interference?

Key to this working properly is that any RF energy on one side of the bifilar choke must be exactly equal to the other side or else the imbalance can actually cause more interference as unequal RF energy from one side would be induced on the other side.

Where does RF noise come from on a power supply?

The noise can be on the AC wiring to the supply or it can be on the DC output of the supply, or both. It is probably common mode on these lines. On the AC lines, it is then radiated by the house wiring and your antenna is very close to that wiring. On the DC output (plus the ground wire) it then gets impressed on the station ground.

This higher frequency of operation is also the reason why switching power supplies often cause interference issues to radio receivers: It is the harmonics from this high-power oscillator that are more likely to be conducted to the outside world via the AC power connector and/or the DC output.

To force the RF energy to be equal is the job of the two capacitors shown – one on the input, and the other on the output. This particular power supply had only a capacitor on the load side of the power supply – where the noise was being generated.

What do you need to know about RF power amplifiers?

RF Power Amplifiers May 7, 2003 2 RF IF Outline ‹PA Introduction zPower transfer characteristics zIntrinsic PA metrics zLinear and Non-linear amplifiers zPA Architectures ‹Single-Stage Linear PA zLoad-line theory zTransistors size zInput and Output Matching zSo why is this so hard? ‹High-efficiency PAs zClass A, AB, B and C amplifiers 3 RF IF