Ultra Broadband DC Blocking OPTI-CAP® Capacitors Dielectric Laboratories / Knowles Ultra Broadband DC Blocking OPTI-CAP® Capacitors offer resonance-free DC blocking to >,40GHz. The series features ultra-broadband low loss, a very low series inductance, and X7R temperature and voltage stability. OPTI-CAP® improves low-frequency stability over temperature and is available in space-saving 0201, 0402, and 0602 footprints.