Impedance, measured in ohms, extends the concept of “opposition” to alternating current (AC) applications. It accounts for resistance, the opposition of current flow, and reactance, the measure of opposing alternating current – an effect of inductance and/or capacitance. In direct current (DC) applications, we talk in terms of resistance, not reactance. Chances are: This isn’t new information. But there’s a reason we wanted to cover this topic – impedance values play an important role in capacitor selection.

Space missions present a unique set of environmental challenges that demand high reliability down to the smallest electronic components. Mission failures could cost human lives. From in-flight systems to power supplies, every single system contributes to the success of a space project, so they must maintain high quality and safety standards for long durations.

To help customers with filter selection, we generally provide a lot of information on what our filters can do. But in this new Filter Basics Series, we are taking a step back to cover some background information on how filters do what they do. Regardless of the technology behind the filter, there are several key concepts that all filters share that we will dive into throughout this series. By providing this detailed fundamental filter information, we hope to help you simplify your future filtering decisions.

In electric vehicle (EV) applications, filter capacitors are a special type of component commonly used as input and output capacitors. Also known as noise suppression or electromagnetic interference (EMI) filters, these particular capacitors act to remove noise and other unwanted signals on the line. On the high voltage alternating current (AC) side of a system, the capacitors often provide EMI filtering, whereas on the direct current (DC) side of a subsystem, they serve to smooth ripple components of the AC and filter out noise.

There are two main mounting schemes for placing components on a printed circuit board (PCB): through-hole technology (THT) and surface-mount technology (SMT). Given its popularity over the last few decades, it’s no surprise that designers default to SMT, but there are advantages to both schemes that are worth exploring, especially for high-reliability application designs.

To help customers with filter selection, we generally provide a lot of information on what our filters can do. But in this new Filter Basics Series, we are taking a step back to cover some background information on how filters do what they do. Regardless of the technology behind the filter, there are several key concepts that all filters share that we will dive into throughout this series. By providing this detailed fundamental filter information, we hope to help you simplify your future filtering decisions. 

To kick-off this series, our first post breaks down the basic properties impacting capacitor and inductor performance including resistance, capacitance, inductance, and impedance.

When an electrical device fails, oftentimes, the root cause can be traced to a field failure of a capacitor. While it is rare for the failure to be caused by a capacitor defect that was introduced during manufacturing, it can happen. This is especially true when multi-layer ceramic capacitors (MLCCs) are used versus other more simplistic capacitor types such as single-layer capacitors (SLCs) since the manufacturing process involves stacking many layers of dielectric and electrodes on top one another.

At this point, you’ve likely seen a slew of mainstream news articles about 5G causing safety concerns around air travel. In fact, ahead of the rollout of new 5G services from major US telecom companies including Verizon and AT&T on Jan. 19, 2022, many international airlines canceled or delayed flights to major US airports where they believed 5G signals could possibly interfere with the radar signals required to properly operate landing equipment on their planes.

In recent years, multilayer ceramic capacitors (MLCCs) have emerged as an excellent capacitor option for the high-power electrical systems needed in electric vehicle (EVs) due to their small physical size, low inductance, and ability to operate at higher temperatures. However, EV engineers are facing two big challenges with using MLCCs including DC bias that can cause capacitance loses of 80 to 90 percent of their quoted value and self-heating issues from AC ripple that can lead to inefficiencies in circuits as well as increased cooling demands. 

At Knowles Precision Devices, we truly do love all things RF. While we are focused on using our expertise in ceramics and thin film manufacturing to innovate on our high-performance filters, our engineers also enjoy keeping up with the trends impacting the entire RF “ecosystem.” This includes dedicating time to experimenting with various open-source RF modeling and analysis tools that we think our potential non-design engineer customers might find useful. One open-source RF and microwave network analysis tool we have been playing around with lately that we feel does a particularly good job is scikit-rf, which is based on the Python programming language.