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Persistence displays retain waveform traces on the screen, allowing them to decay over a user set time duration, they allow users to see a history of signal variations on the screen. This feature is very useful if you are adjusting a signal, as it allows you to see the changes as they are made. Some oscilloscope applications require displaying a history of events in order to see how the signal varies over time. Persistence displays are key tools for viewing such signal changes as a function of time over multiple acquisitions. The most common applications that use persistence displays include jitter analysis of a serial data transmission and eye diagrams used for digital communications systems (Figure 1).

Figure 1 The persistence display of timing jitter on an edge. Multiple acquisitions are retained on the display of the edge to show the variation in its timing. Source Arthur Pini

 This is an analog persistence view of jitter on a clock edge, it is a monochrome display where the brighter areas are the more often occurring signal paths and the duller areas occur less often. The center area of the transition is brighter, meaning more edges pass at that time than during the times corresponding to the outer edges.

The same data can be viewed in color-graded persistence, a tool used to map the frequency of occurrence spectrally. Most frequent events appear in red while the least frequent events are shown in violet (Figure 2).

Figure 2 A color graded persistence display of the same edge jitter. The red areas occur more often than violet areas. Source Arthur Pini

The intermediate frequency of occurrence is mapped spectrally, from most to least often occurring as red-orange-yellow-green-blue-indigo-violet.

Multiple acquisitions are acquired and stored in a persistence map which shows signal variations over time. The persistence decay time is user-selectable with a time constant from half a second to infinite. A saturation control allows users to control the mapping of frequency of occurrence to intensity or color. 

Eye and state transition diagrams

Persistence displays also help analyze data communications signals, where they are used to display eye diagrams and state transition diagrams (Figure 3).

Figure 3 The eye diagrams of the I and Q components and state transition diagrams of a 16-QAM signal rendered in monochrome analog persistence. Source: Arthur Pini

The eye diagrams of a 16-QAM signal show the results of 12,890 acquisitions of the I and Q signal components, which are also cross plotted as an X-Y plot, forming the state transition diagram shown in the upper right corner. Again, the intensity variations are proportional to the amount of time a waveform falls on a particular point on the display. The highly repetitive elements of a signal are brighter than the rarely occurring signal events. The data states, which appear as horizontal lines in the I and Q traces, are written more often and show up brighter than the transitions, which take different paths and occur with less frequency at any given point. The same is true of the state transition diagram where the data states appear as bright dots and the transition paths have a lower intensity.

Persistence histograms

All the data behind the persistence display is available and can be used to quantify the acquired data statistically. One example is to generate a histogram from the persistence display. The oscilloscope used in this article has a function called persistence histogram, it lets the user define either a horizontal or vertical slice through the

persistence display and then forms a histogram as shown in Figure 4.

Figure 4 A persistence histogram with a horizontal slice of the jitter persistence display centered at a level of 0 mV with a width of 10 mV. Source: Arthur Pini

The persistence histogram appears in the trace below the persistence display. Cursors are used to mark the location where the histogram slice originates. In a vertical slice, each bin of the histogram contains a class of related amplitude levels. A horizontal slice, used in the example, produces a histogram where each bin contains a class of related time values.

In the example, the vertical axis of the histogram reads the number of times a specific horizontal pixel is hit. The peak of the histogram corresponds to the central area with a light blue color, while the falling sides correspond to the persistence display changing from indigo to violet. The histogram can be measured using the oscilloscope’s measurement parameters, the measurement parameters P1 through P3 beneath the display grids read the mean, the standard deviation, and the range of the histogram. Parameter help markers annotate the locations of these measurements on the histogram itself.

Persistence histograms can also be applied to eye diagrams showing the horizontal timing uncertainty as well as the vertical deviation (Figure 5).

Figure 5 Application of persistence histogram to an eye diagram permits analysis of noise and jitter on the eye. Source: Arthur Pini

The histogram in the center trace was taken from a horizontal slice through the eye crossing and shows the range of variation in the time of the crossings. The lower histogram was taken using a vertical slice centered between the crossings, it shows the uncertainty in the amplitude of the eye in the center. Some oscilloscopes may not offer measurements that quantify eye characteristics such as eye height and width, .these can actually be obtained using persistence histograms and their associated statistical measurements.

 Persistence trace functions

Persistence trace functions take the histogram of the persistence values over a number of vertical slices set by the user and extract the mean, standard deviation, and range of the persistence data at each slice. It then plots the extracted statistical parameter over time (Figure 6).

Figure 6 Examples of the persistence trace mean (second from the top), persistence trace sigma (third from the top), and persistence trace range (bottom) traces. Source: Arthur Pin)

The persistence trace mean function plots the mean value of the histograms at each of the user’s selected intervals. The resultant plot is the average value of the source persistence trace. In this example, the trace is taken from one thousand points along the persistence trace. This function shows the underlying waveform without vertical noise. Persistence trace sigma plots the minimum and maximum values of the standard deviation about the mean using an extrema plot. The plot shows mean + and – one standard deviation. This function provides a view of the rms noise on the source waveform. The persistence trace range plots the minimum and maximum values of the persistence histogram about the mean and shows the range of the histogram. It is the worst-case range of possible values, especially noise, at each point.

Persistence trace mean is the most useful of the functions allowing a quick determination of the average value of a persistence trace. It is also useful to smooth out traces acquired with low sample point counts (Figure 7).

Figure 7 The persistence trace mean shows all the possible states in waveform with a low sample count by retaining multiple acquisitions. Source: Arthur Pini

Waveforms with low sample counts, displayed with linear interpolation, may appear angular and discontinuous however they are not, and over multiple acquisitions, they trace a smooth waveform. Using persistence trace mean to view the waveform allows the persistence history to fill in the intermediate states and smooth the waveform, showing its actual structure.

3-D persistence display

Adding vertical height to a persistence display proportional to the rate of occurrence gives you a three-dimensional (3-D) effect. This 3-D persistence display creates a topographical view of your waveform.

As shown in Figure 8, this is most useful when studying X-Y plots of signals such as QPSK.

Figure 8 The in-phase and quadrature components of a QSPK signal and a three-dimensional persistence plot of a QPSK state transition diagram. Source: Arthur Pini

The three-dimensional plot retains the color or intensity coding of the persistence displays but adds height proportional to the frequency of occurrence of the display pixels. The shape of these peaks provides an alternative view of the frequency of occurrences in your signals. In this example, the data states of the signal which occur most frequently appear as the highest elements in the X-Y display and are coded in red. Transition paths have more variation and occur less repetitively. They are lower on the display and coded in yellow/green. Off path regions are at the bottom of the display, coded in violet. Controls allow for rotating the 3-D plot to view it from different angles.

The 3-D display can be rendered in three different qualities. The first is as a solid, as is shown, and is the default quality. It can also be rendered in the wireframe quality; this is constructed using lines of equal intensity to create the persistence map. The third quality is shaded, which is only available in monochrome persistence. Shaded quality shows the 3-D object as if it were illuminated by projected light, the shading emphasizes the shape of the object.

The value of persistence displays

Whether used to measure jitter, eye diagrams, or state transition diagrams, persistence is a valuable display technique. When combined with math persistence analysis tools and related measurements, it becomes a powerful tool for quantifying signal variations.

Arthur Pini is a technical support specialist and electrical engineer with over 50 years of experience in electronics test and measurement.

Related Content

• Using oscilloscope X-Y displays
• 10 More tricks to extend oscilloscope usefulness
• Digital oscilloscopes: When things go wrong
• Closing the gaps in your digital oscilloscope waveforms

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Найстаршому альпіністу України Івану Кашину – 100 років! З них понад 60 – разом із КПІ Інформація КП пн, 02/12/2024 - 11:45

КПІ та гуманітарне розмінування medialab пн, 02/12/2024 - 09:59

Wondering what chip resistors are? Then you are in luck because this article will answer that question in detail. Not only that, but we’ll also reveal how they are made, how they work, and the types of technology these devices use. There’s a lot to cover, so let’s get started.

What They Are

Chip resistors aka surface mount devices (SMDs) are integrated circuit devices. They are either rectangular or square. These Resistors are designed to resist the flow of electric current. They are used to regulate, safeguard, and operate circuits.

SMDs can be found in all kinds of sizes. Some are too tiny to pick up with your hands. Values such as E192 and E3 are common values you can readily find.

Surface mount devices are found in most electronic products with advanced circuitry. SMDs are known as such because they are placed directly on the electronic product’s printer circuit board. Without these resistors, there’ll be nothing regulating the current flow within the product. In such a case, the electronic product is subject to damage that can destroy it.

How They Are Made

To manufacture a chip resistor, the end connection of electrode bases is attached to the substrate of a ceramic material. To ensure that the attachment is firm, the resistor is fired. The next step is the printing or depositing of the film of a resistive material. Again, the resistor is fired.

Afterward, several layers of protective coat are used to cover the resistor. You can click here to find out more about the protective coating. Before the application of the next coat, the previous one is allowed to dry first.

The addition of these protective coatings is beneficial to the SMD and the electronic product. First of all, the protective coating protects the resistor from mechanical damage. Secondly, it prevents contaminants and moisture from affecting these devices.

Chip resistors with large surfaces are designed with a marking. When packaged these devices resemble blister rolls. They can then be used on pick-and-place electronic machines.

How They Work

Chip resistors are designed to restrict the flow of circuit current. These chip resistors sometimes are designed with a definite resistance value. This type is known as a fixed resistor.

On the other hand, the resistance value of the second group isn’t definite but is designed to operate within a range. This type is known as a variable resistor or potentiometer. Because of its passive function, a resistor only decreases voltage or current signals.

The perfect resistor is linear. In this case, the instantaneous current that passes through the SMD is proportional to the instantaneous voltage being applied. Resistors that do not operate linearly include varistors and thermistors.

In electronic circuits, these SMDs are formed into several series based on resistance value and power. Surface mount devices act as voltage dividers and shunts to control and steady voltage and current in circuits. You can visit https://eepower.com/ to learn more about shunts in circuits. They also serve as circuit-matching loads.

Chip Resistor Technology

Manufacturers can choose from different technologies when manufacturing an SMD. These different technologies have their advantages and disadvantages. The following are the most commonly used chip resistor technologies:

Thin Film

Chip resistors manufactured with this technology are made by depositing a thin metallic coating on the upper part of a ceramic substrate. Due to this design, these devices have greater resistance for a certain area. As such, they are economical and space-efficient.

The downside is that they are prone to failure. The reason for this is that they can easily heat up or be affected by water vapor. Chemical contamination is another reason that can lead to the failure of these SMDs.

Thick Film

These are made by applying the paste of a restive metal onto a base. Because of this, the resistance they provide for a certain area is usually high. Furthermore, they are cheaper when you compare them to other resistor types such as wire-wound resistors.

The disadvantage of using this technology is it produces more noise compared to thin-film resistors. Although they have similar frequency response to thin films, they are still noisy. Despite this, they are still very used in circuit units that don’t require durability and accuracy.

Foil

This technology involves the use of a metallic foil applied to a ceramic substrate. It is then photo-etched via a restive pattern. The result is a resistor with enhanced stability, low capacitance, reduced noise, and non-inductance. All these benefits are achieved without losing precision and speed. As such, these surface mount devices are in high demand.

Reading a Chip Resistor Code

These devices are usually marked with a code known as SMD Resistor Codes. The code might be made of three or four digits. The purpose of this code is to reveal the device’s resistance value.

To interpret a code with three digits, take the first two digits as a standalone number and the third digit as a standalone number. The first two digits are the significant resistance number while the third digit is the multiplier. You use the third digit to multiply the first two to get the resistance value.

For a code with four digits, take the first three digits as a standalone number and the fourth digit as a standalone number. The first three digits are the significant resistance number while the fourth digit is the multiplier. You use the fourth digit to multiply the first three to get the resistance value.

Chip Resistor Advantages

They do not take up much space in a product. Having several connections for every single component is proof of their high component density. Also, they have a simpler automated assembly and are much faster.

Because of their structured design, the PCB has fewer holes bored into it. You can visit https://www.techtarget.com/ to learn more about the Printer Circuit Board. Also, they can be on either side of the PCB. Their mechanical performance is enhanced, and they have cheap parts.

Chip Resistor Disadvantages

Their solder components can be prone to damage which happens via thermal cycling that moves potted compounds. Also, the component packages they are designed with prevent them from being installed into sockets. Furthermore, when there is a need for reassembling or repair, an expert must handle it and extensive tools are required.

Conclusion

In this article, we’ve discussed what you need to know about chip resistors. We discussed what they are, how they are made, how they work, and the technologies used in making them. We also revealed the advantages and disadvantages of these devices.

The post What You Need to Know About Chip Resistors appeared first on Electronics Lovers ~ Technology We Love.

In this project, we’ll use a Raspberry Pi Pico to build an adjustable clock with an LED display. We’ll then integrate the clock with a Radio Shack Science Fair Microcomputer Trainer programmed to function as a 7-bit binary counter.

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КПІшниці, з Міжнародним днем жінок і дівчат у науці! medialab нд, 02/11/2024 - 11:47

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КПІ — перший за популярністю в Інтернеті medialab сб, 02/10/2024 - 20:40

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During his long and remarkably productive career, Jay Forrester accumulated an impressive list of innovations and achievements in electrical engineering, social science, and business management.

In this news analysis piece, Nthatisi examines Silicon Labs’ High Accuracy Distance Measurement (HADM) solution, which leverages Bluetooth LE's Channel Sounding feature, designed for complex RF environments.

For its fiscal third-quarter 2024 (to 30 December 2023), Qorvo Inc of Greensboro, NC, USA (which provides core technologies and RF solutions for mobile, infrastructure and defense applications) has reported revenue of $1073.9m, down 2.7% on $1103.5m last quarter but up 44.5% on $743.3m a year ago. This exceeds the high point of the guidance range (of $1bn, plus or minus $25m) by $49m. “Revenue continues to benefit from significant content gains at our largest customer,” says chief financial officer Grant Brown...

Two wideband current sensors from Allegro, the ACS37030 and ACS37032, ensure efficiency and reliability in GaN and SiC FET power architectures. With an operating bandwidth of DC to 5 MHz, the devices are suitable for electrified vehicles, clean energy solutions, and data center applications.

The ACS37030 and ACS37032 offer current sensing ranges of ±20 A, ±40 A, and ±65 A, with a typical response time of 40 ns. Both devices employ dual signal paths. One path captures low-frequency and DC current using Hall-effect elements. The other path captures high-frequency current data through an inductive coil. These two paths are summed to enable sensing from DC to 5 MHz in a single device.

The current sensors achieve stable and safe control, while reducing EMI. Sensitivity error over temperature is ±2%. The properties of the inductive coil increase signal to noise ratio (SNR) as frequency increases, minimizing noise at the output. The ACS37030 provides a zero current reference output, while the ACS37032 offers an overcurrent fault output.

Housed in compact 6-pin SOIC packages, the sensors have a rated isolation voltage of 3500 VRMS and a basic working voltage of 840 VRMS. They operate over a temperature range of -40° to +150°C. To learn more about the ACS37030 and ACS37032 current sensors, click here.

Allegro MicroSystems

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MaxLinear is offering a product design kit (PDK) to help cable manufacturers integrate the Keystone PAM4 DSP into their active electrical cables. According to MaxLinear, the 5-nm PAM4 DSP can yield up to a 40% power savings over competitor solutions when used in active electrical cable (AEC) applications.

Unlike passive cables, active electrical cables actively boost signals, allowing for longer distances (up to 7 meters for 400G); higher bandwidth; and thinner, lighter cables. Keystone PAM4 DSPs based on 5-nm CMOS technology enable designers to build high-speed cables that maximize reach and minimize power consumption in next-generation hyperscale cloud networks. To ease DSP integration, the PDK includes strong application support, multiple tools to optimize and monitor performance, and both hardware and software reference designs.

Keystone 5-nm DSPs cater to 400G and 800G applications and provide a 106.25-Gbps host-side electrical I/O that aligns with the line-side interface rate. Variants support single-mode optics (EML and SiPh) and multimode optics (VCSEL transceivers and AOCs), as well as AECs. The family also includes companion transimpedance amplifiers.

For more information about the Keystone 5-nm PAM4 DSPs (MxL93642, MxL93643, MxL93682, and MxL93683), click here.

MaxLinear

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Sara-R520M19, an LTE-M and NB-IoT module from Swiss provider u-blox, delivers accurate positioning data concurrent with LTE communication. Simultaneous GNSS and cellular connectivity is an important factor for applications requiring continuous or cyclic tracking, such as utility metering and asset tracking.

The Sara-R520M10 module incorporates the company’s UBX-R52 cellular chip, M10 GNSS receiver, and dedicated GNSS antenna interface in a 16×26×2.2-mm, 96-pin LGA package. A variant without the GNSS receiver, the Sara-R520, is also available for general-purpose applications. This model features SpotNow, an assisted GPS receiver for applications requiring occasional tracking. 

The Sara-R52 series offers 23 dBm of RF output power to ensure stable connectivity. Modules include an Open CPU (uCPU) feature that allows users to run their own software on the chip without the need for an external MCU. An onboard smart connection manager performs automatic connectivity management. Its function is to achieve either the best performance or the lowest power consumption. This is useful when a connection is lost and needs to be re-established.

In addition to the Sara-R52 series, u-blox released the Lexi-R520 LTE-M module. The Lexi-R520 furnishes the same features as the Sara-R520, but in a smaller form factor. Its 16×16×2-mm, 133-pin LGA package lends itself to applications like wearables.

Samples of the LTE-M modules are available now, with volume production scheduled for Q3 2024.

Sara-R52 series product page

Lexi-R520 product page

u-blox

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