Compact LTCC filter with 7th-order harmonics suppression for 5G N77 band applications

Abstract

A compact dual-mode band-pass filter (BPF) with 7th-order harmonics suppression is proposed. The proposed dual-mode BPF is designed using a three-section stepped-impedance-variable feeding line (SIVFL) and a square resonator. The high-order harmonics suppression is achieved by the SIVFL structures, and the size reduction is achieved using meandered lines and a resonator with two degenerate modes. The proposed BPF has a wide stopband up to 7th-order harmonics and a compact size of only 7 × 7 × 0.3mm. The proposed BPF is suitable for the fifth-generation (5G) N77 band applications due to its working frequency, compact size, and good performance. Comparison and discussion are implemented as well.