A compact folded interdigital bandpass filter using LTCC technology

A compact folded interdigital bandpass filter using low temperature co-fired ceramic (LTCC) technology is proposed. Strong capacitive couplings between the double-layer coupled stripline resonator structure are introduced to realize miniature bandpass filters. A design of an eight-pole Chebyshev folded filter with such structure is performed in this paper. The simulation response exhibits an insertion loss of 0.6dB, a return loss of 19 dB and relative band width of 34%. The compact size of this folded interdigital bandpass filter is 12⋆7⋆2.7mm 3 , which is less than λ/ 8 ×λ/12 ×2.7mm 3 .