Patent ID: 6995636

Claim:
An in-band-flat-group-delay type dielectric filter, comprising: a plurality of dielectric resonators, a main circuit formed of series coupling capacitors, with which the dielectric resonators are coupled to one another; and an auxiliary circuit for coupling the main circuit to capacitors by bypass coupling, wherein both deviations in group delay time and in amplitude between input/output terminals fall within specified certain deviation values, respectively, at the same time at a center frequency and within a specified frequency band around the center frequency, the auxiliary circuit includes parallel bypass capacitors and series bypass capacitors; two of the series coupling capacitors connect between the adjacent dielectric resonators; each one end of the parallel bypass capacitors is connected to a junction between the two of the series coupling capacitors; and the other ends of the adjacent parallel bypass capacitors are connected to be short circuited or via at least one of the series bypass capacitors.