Product enclosures have frequency resonances that can produce unwanted EMI. Absorption materials in the cavity can reduce EMI. Use a cookie tin to compare materials before inserting them into your product. As operating frequencies approach microwaves, enclosures can appear as resonant cavities and amplify EMI emissions. When I was working on space shuttle communications systems, […]
FAQ
How to choose analog-signal-chain components: part 1
Signal conditioning can prepare a sensor’s output for digitization. In a previous series, we looked at the analog-to-digital converter (ADCs) and sources of error that occur within the device. Of course, errors can creep in upstream of the ADC along the analog signal chain as the signal to be digitized is acquired and conditioned. Q: […]
Understanding ADC specs and architectures: part 5
ENOB describes an analog-to-digital converter’s performance with respect to total noise and distortion. In the earlier parts of this series on analog-to-digital converters (ADCs), we looked at the basics (part 1); gain error, offset error, and differential nonlinearity (part 2); and integral nonlinearity (part 3); and then we looked at some ADC topologies and introduced […]
How you can use smart design to enhance rare earths recycling
Rare earth elements (REEs) are important for society because they enhance the performance of a wide range of green energy, industrial, medical, aerospace, and consumer devices. They are rare because, while not uncommon, they are widely dispersed in the Earth’s crust and not generally found in high concentrations. That makes their extraction difficult and expensive. […]
Understanding ADC specs and architectures: part 4
The AC performance of an analog-to-digital converter depends on its architecture. In part 3 of this series, we discussed the integral nonlinearity (INL) error of an analog-to-digital converter (ADC), noting that gain, offset, and INL error all contribute to the total unadjusted error. This metric provides an overall view of an ADC’s DC performance. Q: What about the AC […]
Understanding ADC specs and architectures: part 3
Integral nonlinearity tracks the cumulative effects of an ADC’s differential nonlinearity. In part 2 of this series, we discussed several sources of error in an analog-to-digital converter (ADC), including gain, offset, missing-code error, and differential nonlinearity (DNL). We concluded with an illustration of a waveform with varying levels of DNL superimposed on the staircase representing […]
Understanding ADC specs and architectures: part 2
Specifications such as gain error, offset error, and differential nonlinearity help define an analog-to-digital converter’s performance. In part 1 of this series, we discussed an ideal analog-to-digital converter (ADC), noting that it would have infinite resolution and bandwidth. Then we looked at the real world of practical inverters and how their resolution, expressed in a […]
Understanding ADC specs and architectures: part 1
Analog-to-digital converters are the heart of most test equipment, setting the stage for the digital processing of analog signals. Several posts over the past year or so have involved digital signal processing. For example, we have covered the fast Fourier transform (FFT), the inverse FFT, and discrete convolution. To perform these operations on real-world signals, […]
Phone chargers produce EMI: We compared four
The switching power supplies that regulate output voltage produce radiated emissions. Our tests compare waveforms that give clues as to how the chargers operate.
Characterize EMI from dc-dc converter ringing
Switching power supplies produce radiated and conducted emissions caused by ringing. Oscilloscope and spectrum-analyzer measurements let you see them. DC-DC converters are ubiquitous in most electronic products. While more efficient than linear regulators, they can also produce considerable amounts of interference that can affect nearby circuits. The measurements in this article show how ringing occurs […]
