Band reject, or notch, filters are used to reject a narrow frequency band and pass a wide frequency range. Traditionally, BRF’s are custom designed for each specific frequency application.
AVX’s Accu-P Thin-Film RF capacitors are a simple BRF that is both cost effective and miniature. Until recently, most high frequency/microwave capacitors were based on fired-ceramic (porcelain) technology. Layers of ceramic dielectric material and metal alloy electrode paste are interleaved and then sintered in a high temperature oven. This technology exhibits component variability in dielectric properties (losses, dielectric constant and insulation resistance), variability in electrode conductivity and variability in physical size. The Thin-Film Capacitors developed by AVX virtually eliminate these variances. Thin-Film technology is commonly used for producing semiconductor devices. In the last two decades, this technology has developed tremendously, both in performance and in process control.

Today line definitions of below 1 μm and layer thickness control of 100Å (10-2 μm) are possible. Applying this technology to the manufacture of capacitors has enabled the development of components where both electrical and physical properties can be tightly controlled.

Read more: http://www.avx.com/docs/techinfo/accupthin.pdf