Tag: EMI

Philips Sonicare Electric Toothbrush Measurements without Teardown

Part I: Sonicare Electric Toothbrush Architecture Figure 1: Sonicare Electric Toothbrush Architecture This electric toothbrush is a water-resistant design, thus it adopts wireless charging technology. Coil 2 is the wireless charging receiver. A permanent magnet is attached to the trail

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Preamplifier 30 MHz to 6 GHz

Part I: Introduction I designed two preamplifiers which can be added to any application needs additional gain. The two designs have the same PCB layout but different IC U1 which is shown in the Figure 1. The PCB is shown

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Channel power measurements

Part I: Understanding the RF Spectrum Measurements The Spectrum Analyzer has a bandpass filter (IF filter) which is used as the "window" for detecting signals. The bandpass filter's bandwidth is also called the resolution bandwidth(RBW) of the analyzer and can

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Electromagnetic Shielding

Part I: Selecting the Proper Shielding Materials At first, we need to introduce a physics concept Skin Depth, before discussing the shielding materials. The Skin Depth δ is defined as the depth below the surface of the conductor at which the

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Measuring EMI with Homemade Magnetic Field Probe

Part I: Magnetic Field Probe The theories behind the Magnetic Field Probe (Near Field Probe) is not very complex. Roy Ediss well stated the theories and the various designs of the Magnetic Field Probes in his article, Probing the Magnetic

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