Planar comb(-)line filters with minimum adjacent capacitive(-) coupling effect

Abstract

A comb-line filter is disclosed which includes: (a) a top metal plate and a bottom metal plate; (b) a pair of resonators sandwiched between the top and bottom metal plates and in a parallel and spaced relationship with respect to the top and bottom metal plates; (c) a pair of resonator extensions extending from the pair of resonators, respectively, and (d) a pair of capacitor plates provided above and below the pair of resonators, respectively. The pair of capacitor plates and the pair of resonators extensions are grounded so as to provide a double-parallel capacitor groups. The comb-line filter can be constructed such that the ratio of the separation between the two resonators (d2) and the separation between the resonator and the capacitor plate (d1) is above about 3. By doing so, the coupling capacitance can be reduced to 0.1 pF or lower. In a more preferred embodiment, the ratio of d1/d2 is maintained to below 10, and the coupling capacitance will be essentially zero (less than 0.01 pF).

Dependencies are inferred from the claim text.