Compact LTCC balanced bandpass filter using distributed-element resonator

Presented is a vertically and horizontally folded half-wavelength resonator in a three-dimension (3D) environment and its application to a balanced bandpass filter (BPF). Benefiting from the multilayered resonator based on the transmission line theory and low temperature co-fired ceramic (LTCC) technology, the proposed balanced BPF can obtain compact size and good performance. For demonstration, a LTCC balanced BPF centred at 2.45GHz has been designed using the proposed resonator, and the size of the circuit is 6.0 × 5.0 × 1.6 mm³.