About Knowles Precision Devices

Knowles Precision Devices, leading global innovator of high-performance solutions.

At Knowles Precision Devices, we make Multilayer, High Reliability, Single Layer and Precision Variable Capacitors; Aluminum Electrolytic, Mica, and Film Capacitors; EMI Filters; and RF/Microwave Components including RF Filters, Splitters and Couplers. Our business was formed by combining Compex Corporation, Dielectric Laboratories, Johanson Manufacturing, Novacap, Syfer, and Voltronics, each well-established specialty component makers with a combined history of more than 200 years, into a single organization.
Our expertise is the design and manufacture of high-performance components important to engineers in applications where function and reliability are key. The markets we serve include medical implantable and medical equipment, military,
aerospace/avionics, electric vehicle and automotive, EMI and connector filtering, oil exploration, instrumentation, industrial electronics, optical networks, and new energy.  
Our capacitors and RF devices are used in some of the most complex and mission-critical applications, from 8000 feet below the earth’s surface to orbiting 254 miles above us on the International Space Station to Mars and beyond. If you have a complex technical challenge with hard-to-meet performance, size, or reliability requirements, bring it to us. It’s what we do.

A Short History of Knowles Precision Devices

  • In 1985 Dielectric Laboratories, DLI (High-Q Multi-Layer Capacitors and Single-Layer Capacitors, Resonators, Filters, Broadband DC blocks, Thin Film components) became part of Dover Corporation. DLI had previously invented the Single Layer Capacitor in 1974.
  • Shortly after in 1987 Novacap (specialized MLCC products to serve unique and difficult high reliability, military and space requirements) joined the family.
  • In the year 2000 Syfer (MLCC products to serve demanding commercial and industrial requirements) came on board, having just invented Flexicap, an approach to avoiding MLCC cracking that the entire capacitor industry has since adopted. At the same time we created the Cap-Rack approach to increasing capacitance in a reduced footprint.
  • Voltronics (world leader in precision variable capacitors) was brought in in 2004 to expand our multi turn trimmer capabilities.
  • Further development of high CV capacitors followed with the creation of StackiCap technology in 2012.
  • In 2014 Knowles Corporation was established as a publicly traded company. DLI, Novacap Syfer and Voltronics formed the new Precision Devices division.
  • Johanson Manufacturing, a world-class supplier of trimmer capacitors, non-magnetic variable inductors and microwave tuning elements, joined our company in 2017.
  • To complement our existing strengths in Single Layer Capacitors, Compex was acquired in 2018.
  • IMC joined Knowles Precision Devices in 2021 to further bolster our RF and microwave solutions portfolio.
  • Cornell Dubilier, a leading manufacturer of high-quality film, electrolytic and mica capacitors joined the Knowles family in 2023.