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.

When constructing multilayer ceramic capacitors (MLCCs), there are two classes of dielectrics electrical engineers typically select from depending on the application – Class 1, which consists of non-ferroelectric materials such as C0G/NP0, and Class 2, which are ferroelectric materials such as X5R and X7R. One key difference between these materials comes in the form of capacitance stability as voltage and temperature increase. With Class 1 dielectrics, capacitance will remain stable when DC voltage is applied and operational temperature increases. On the other hand, Class 2 dielectrics, which have a higher dielectric constant (K), are less stable with regards to temperature, voltage, frequency, and time.

The generation of RF energy is critical for a wide range of technologies including magnetic resonance imaging (MRI), semiconductor manufacturing, industrial lasers, and wireless charging systems that require high-frequency current and minimal instances of power loss. For example, with an industrial laser, the RF plasma excitation, which is when electrons are broken off an atomic bond and plasma forms, requires RF sources ranging from 1kHz to 40.68MHz depending on the energy required, and a CO₂ laser RF power supply that contains a standard source at 13.56MHz, 81MHz, or 125MHz.

Designing medical implantable devices for high reliability is crucial for a variety of reasons. First, given the life-critical functions performed by many medial implantable devices, and the invasive procedure required to implant medical equipment properly in the human body, it is imperative that all medical devices are designed to function reliably throughout their entire lifetime. Furthermore, since patient safety is paramount, any precautions to reduce the possibility of potentially life-threatening malfunctions, recalls, and replacement surgeries are necessary. And, beyond preventing patient safety issues, there may also be severe economic and legal implications for device manufacturers if an implantable device fails.

Today, one of the most cost-effective and flexible electrical interconnection techniques available is wire bonding. With this technique, thin wire and a combination of heat, pressure, and/or ultrasonic energy are used to create a connection between an integrated circuit or other semiconductor devices and device packaging.

Trimmer capacitors are variable components used to calibrate RF circuits during manufacturing or servicing. These components allow for variable tuning--think oscillator frequency values or rise and fall times. Should values drift over the life of the device, trimmer capacitors can be recalibrated as needed. For sensitive applications like magnetic resonance imaging (MRI), these components help to optimize performance where any instability in time or temperature could impact the image output.