KI SMD Wire Sound Ceramic Inductors Würth Elektronik KI SMD Wire Sound Ceramic Inductors have an excellent Q factor and the highest possible self resonant frequencies up to 12.5GHz. Würth Elektronik KI SMD Wire Sound Ceramic Inductors have inductance tolerances of 5% (2% on request), high thermal stability, and an operating temperature of -40ºC to +125ºC. This series was created for use with high frequency applications.