Signal Integrity Consulting

An electrical signal’s quality is measured using a set of criteria known as signal integrity, or SI. A voltage (or current) waveform in digital electronics represents a stream of binary values.

However, since digital signals are inherently analog, they can all experience consequences like noise, distortion, and loss. This can be successfully transmitted using a straightforward conductor over short distances and at low bit rates.

The electrical signal may degrade at high bit rates, over longer distances, or across a variety of media, to the point where mistakes arise and the system or device malfunctions. Analysis and mitigation of these effects are tasks of signal integrity engineering.

Inter-System Connection Analysis

The internal connections of an integrated circuit (IC), the package, the printed circuit board (PCB), the backplane, and inter-system connections are all key components of the electronics packaging and assembly process. The approach to signal integrity for on-chip connections versus chip-to-chip connections differs significantly, despite the fact that there are some common themes at these different levels. These practical concerns include the interconnect flight time versus the bit period, in instance.

Crosstalk, ground bounce, distortion, ringing, signal loss, and power supply noise are a few of the major problems that need to be taken into consideration for signal integrity.

The grating effect in photos and video that appears as rippling artifact around sharp edges is known as the Gibbs phenomenon in mathematical methods of image processing. The loss or distortion of high frequency information in the image is what results in this effect. It is present in a variety of image types, including MRI images, compressed images, sharpened images, and images sent through analog channels.

In most cases, ringing is added to an image following various image processing methods. It appears following picture and video compression the most frequently. This artifact can range from being undetectable to being inconvenient, depending on the image type, compression methodology, and compression setting. Additionally, aggressive image sharpening might produce false edges close to sharp edges.

Analyzing the Frequency Domain

In rare circumstances, the ringing effect can be initially seen in the source images, such as in MRI images. The output of an MRI is frequency domain information about the picture. When the MRI sample rate is low, ringing effects in the spatial domain arise after picture reconstruction. Analog television is another example of the ringing effect that is initially exhibited. Color and brightness components (Y) make up the transmitted TV signal (U and V).

Compared to luminance components, the bandwidth for color components is less. This causes color ringing and the loss of high frequency information in color components. If the signal quality is poor, the brightness component will also exhibit ringing. In contemporary TV sets, sharpening filters also cause ringing.

Power electronic converter dependability and maintainability can both be improved through condition monitoring, which has been proven to be both efficient and affordable. Power transistor switching transients in power electronic converters result in high-frequency oscillation, or ringing.

The parasitic capacitance and stray inductance values in the oscillation loop have a significant impact on the ringing frequency. Despite being a significant contributor to the ringing, circuit stray inductance does not alter with transistor age.

For power transistors, a change in the junction capacitance or the internal inductance is a crucial failure indicator. Ringing frequency can therefore be used to keep an eye on the condition of power transistors. However, the power transistors’ switching operations frequently produce a dynamic behavior.

Fast Fourier transformation (FFT)

This dynamic behavior can actually produce oscillation signals that are masked by background noise, making it challenging to determine the ringing frequency directly. Our signal integrity consulting engineers frequently suggest a frequency extraction method based on empirical mode decomposition (EMD) and Fast Fourier transformation (FFT).

In short, the suggested procedure is straightforward and highly precise. The ringing analysis is validated using simulation findings, and the effectiveness of the suggested techniques for connected clients is validated using testing results.

As we’ve seen, resonance happens when a system’s inherent frequency and any anticipated imposed vibration frequencies (such imbalance), which might result in extremely high vibration levels, coincide. What may be done to stop or lessen the effects of a resonant state if it is determined that resonance is the real source of excessive vibration?

The two main parameters that affect a system’s natural frequency are mass and stiffness. If w, then w = sqrt(k/m), if w is the natural frequency.  Additionally, where m is the mass and k is the stiffness. Therefore, we must modify either k or m, or both, in order to adjust the natural frequency.

The goal is often to raise the natural frequency so that it exceeds any anticipated vibration frequencies. The resonance will probably not be aroused if the natural frequency is higher than or much outside of any anticipated vibration frequencies. Any structural redesigns carried out to prevent resonance are based on this hypothesis.

Shifting Natural Frequency to Reduce a System’s Vibration Response

The following guidelines can be utilized in practice to change a natural frequency and reduce a system’s vibration response:

• The natural frequency is increased by adding stiffness.
• When mass is added, the natural frequency is lowered.
• The peak response is decreased as damping is increased, but the response range is expanded.
• Increasing the peak response while decreasing dampening narrows the response range
• Resonance response is reduced when driving amplitudes are decreased.

What Leads to PCB Ringing?

Ringing is a voltage or current output that oscillates like a ripple on a pond when we’re talking about a printed circuit board or other electronic systems.

Ringing is occasionally referred to as “ripple” due to the distinctive form of the output signal. However, when employing AC switched power supplies, ripple often refers to output specifically when the supply fails to effectively or properly suppress the AC waveform.

 

What causes cross-linking agents to ring?

Apart from power supply, the cause of ringing relies on how “long” or “short” your traces are. As a general rule, traces are regarded as “long” if the propagation time from the source to the load and back is longer than the printed-circuit signal rise time. For a starting point on line length and reducing transmission line impacts like ringing if you happen to be dealing with stripline or microstrips, we suggest referring to an engineering expert.

Returning to long and short traces, ringing is brought on by parasitic inductance and capacitance when the trace is short. The parasitic elements resonate in response to a pulse or abrupt shift in the input.  This takes place in their typical frequency range, causing your output to ring. The reason of ringing on long traces is more frequently signal frequency reflection from an impedance mismatch.

 

What effects will ringing have on a multilayer circuit board?

It’s wonderful if a noisy oscilloscope doesn’t lead you to experience an existential crisis.  Ringing, however, can have some detrimental effects on both your life and product design.

Increased EMI:

• Ringing can and frequently does cause interference and noise. This could conduct or radiate across your ground plane, causing all the corresponding performance issues.

Increased Current Flow:

• Ringing increases the amount of current that flows through your circuit. This results in an increase in the amount of power used by your device (and a reduction in battery life), but it also unexpectedly heats up extra ground plane parts. That might make them less useful and last less time.

Decreased Electronic Performance:

• Ringing causes performance declines across a number of measures in addition to the cumulative performance losses brought on by the elevated current and heating. Due to the settling period, you will have a lag in output, which will cause your circuit board’s vias and responsiveness to decrease. Your outputs will likewise have much lower resolution.

Decreased Data Integrity:

• Ringing might be particularly destructive if your circuits are digital. All of the issues we’ve discussed are still present, but the bar is significantly lower. You’re more likely to get mistakes and damaged data if you combine this with any supply rail noise.

Audible Feedback:

• In audio and video applications, ringing takes a distinctive form. You’ll hear ripple if it happens in the audible range of your output. In visual displays, it also produces observable artifacts.

In networking, signal attenuation equals signal loss. During transmission, the signal strength weakens or is lost. This is a typical side effect of long-distance signal transmission. A signal’s amplitude decreases as its wavelength increases in distance, making it weaker. This holds true for analog and digital signals sent via wired and wireless transmissions.

Causes of signal attenuation other than distance include:

• Long cabling – Signals that are transmitted over a long distance gradually lose power.
• Wire size – Because thinner cables are more susceptible to outside interferences, they attenuate more than thicker wires do.
• Signal Noise – Adjacent cables may produce electromagnetic interferences, which is noise. The attenuation increases as the noise level rises.
• Defective Materials – Faulty conductors and connections Attenuation results from improperly installed connectors and conductors.

Both technicians and operators need to be aware of how much the coax and fiber-optic cables they are installing attenuate signals. At the time of installation, calculating, measuring, and testing the signal attenuation for the cabling aids in immediately preventing problems. The worst case scenario is signal power loss as a result of attenuation dropping so low that communication to the network gateway is lost. Customers become dissatisfied as a result, and operators experience increased time and financial problems.

The type of cable, the distance it is traveling, and the radio signal’s frequency all affect the amount of loss across coax cable. Even if signal attenuation occurs frequently, it’s crucial to setup the measurement levels correctly. Decibels (dB) are units used to measure signal attenuation (signal loss) per unit of distance.

Diagnostic Tools for Signal Integrity

The Ansys EMA3D Cable is a multi-tool that carries out each of the significant tests needed by a field professional to precisely and quickly diagnose problems both inside and outside the home. such as visual displays of test and measurement data, as well as attributes like:

• Calculating for signal loss
• Embedded pressure gauge
• How to recognize signal noise
• Automated spectrum evaluation
• RF channel scanning, and more

Networking technologies from Ansys can be used together to form a very potent toolkit that offers cost reductions, time savings, efficiencies, and consistent metrics with little training required. With embedded certification testing tools, you can equip your professionals to troubleshoot the entire house for a fraction of the price of alternative alternatives.