Composite filter comprising a surface acoustic wave filter and an LC filter

1. A composite filter comprising:

a piezoelectric substrate;

a surface acoustic wave filter;

an LC filter coupled to the surface acoustic wave filter; and

a laminated substrate;

wherein the surface acoustic wave filter is formed by combining surface acoustic wave resonators having comb-shaped electrodes that oppose each other along a first opposing direction on the piezoelectric substrate;

wherein the LC filter comprises a π-shaped LC filter formed of a first capacitor and a second capacitor coupled to an inductor in a π-shape, and a third capacitor coupled in parallel to the inductor;

wherein at least one of the first, second and third capacitors is formed of comb-shaped electrodes opposed to each other along a second opposing direction on the piezoelectric substrate, and the second opposing direction of the comb-shaped electrodes differs from the first opposing direction of the comb-shaped electrodes of the surface acoustic wave resonators;

wherein the piezoelectric substrate is provided with a first grounding conductor disposed at a place not confronting a top face or an underside of the inductor, and the first and second capacitors of the π-shaped LC filter are coupled to the first grounding conductor; and

wherein other inductors coupled to the first and second capacitors respectively are provided by coupling a second grounding conductor embedded in the laminated substrate with the first grounding conductor.

2. The composite filter of claim 1 , wherein the piezoelectric substrate is layered on a dielectric substrate and the inductor is embedded in the dielectric substrate.

3. The composite filter of claim 1 , wherein comb-shaped electrodes forming the first capacitor and the second capacitor are covered with dielectric.