Electronic devices power our world and allow us to communicate. In all applications requiring signal integrity and accurate power amplification, blocking capacitors are used to provide clean waveforms and correctly amplified voltages.

Electronic devices provide the tools we need to power the world. From cell phones to modern vehicles to scientific equipment to the appliances in our homes, we rely on electronics to improve and even lengthen our lives. All electronics depend on clean power, and the bypass capacitor is crucial in ensuring devices safely meet their power specifications.

To protect people and critical equipment, military-grade electronic devices must be designed to function reliably while operating in incredibly harsh environments. Therefore, instead of continuing to use traditional silicon semiconductors, in recent years, electronic device designers have started to use wide band-gap (WBG) materials such as silicon carbide (SiC) to develop the semiconductors required for military device power supplies. In general, WBG materials can operate at much higher voltages, have better thermal characteristics, and can perform switching at much higher frequencies. Therefore, SiC-based semiconductors provide superior performance compared to silicon, including higher power efficiency, higher switching frequency, and higher temperature resistance as shown in Figure 1.

From industrial to automotive to aerospace applications, power electronics are demanding higher capacitance in smaller packages. Therefore, to meet both capacitance demands and size requirements, electronic designers simply cannot continue to add more capacitors. While capacitor stacking is an option, many stacked assemblies are still quite large and stacking often introduces new failure modes, such as piezo electric cracking (Figure 1). 

As interest and adoption increase in the electric vehicle (EV) arena, associated technologies are advancing quickly. Batteries are becoming more powerful and charging infrastructure is increasingly robust and efficient. With all these advancements, EV batteries are good for more than powering cars on the road.

High-speed broadband and fiber optic devices used across a variety of communication and military and aerospace applications require circuits that couple RF signals. Since this involves removing the DC component and allowing only the high-frequency AC component to pass or bypass, this can be a complicated process. The blocking capacitor needs to present a near reflectionless transition at the frequency the line is seeing and at a bandwidth that allows the entire signal to pass without degradation. 

As the backbone of the X-ray machine, X-ray tubes produce the radiation that generates the electromagnetic waves known as the “X-ray.” This is done by using a high voltage to accelerate the electrons released by a hot cathode to a high velocity. Those electrons then collide with the anode, which is a metal target usually made of tungsten. This process requires an input voltage typically ranging from 180 to 480 VAC with a power supply that transforms and steps up the voltage to extremely high voltage outputs ranging from 10kV and 120kV DC. A high-level diagram of the power supply required to power the X-ray tubes is shown in Figure 1. 

At Knowles Precision Devices (KPD), we handle the specialty components that go in the systems that can’t quit. We have the extensive resources and subject matter knowledge to innovate around the technical and environmental challenges facing high-impact industries including military, aerospace, and beyond.

From military aircraft to electronic warfare defense systems, aerospace and defense applications are placing new demands on their power electronics. Defense electronics systems must function reliably for their lifetime while operating at higher voltages and wider temperature ranges, and all while becoming smaller, lighter, and consuming less power.

As demand for high-efficiency and high-power-density inverters continues to grow, the so-called “flying” capacitor multilevel inverter is emerging as a strong choice for many power electronics systems. Since these capacitors can “float” to different electric potentials depending on the connected semiconductor switching structure and state, they help balance out voltage level differences due to manufacturing tolerances, temperature variations, and other factors. These capacitors are also helpful in balancing voltage across the structure by temporarily storing and releasing energy as needed, increasing power density and quality, and optimizing the use of existing voltage availability.