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 0.6 dB, a return loss of 19 dB and relative band width of 34%. The compact size of this folded interdigital bandpass filter is 12*7*2.7 mm
³
, which is less than λ / 8 × λ / 12 × 2.7 mm
³
.