Compact LTCC filter with wide stopband for 5G applications

A compact bandpass filter (BPF) is proposed with dual composite right/left‐handed resonators for the fifth‐generation (5G) N79 band applications. With consideration of compact size and filtering performance simultaneously, the vertical and horizontal finger constructed capacitor is improved with respective dimensions for each finger to obtain larger capacitance and better filtering performance. The proposed BPF is built in a four‐layer low‐temperature co‐fired ceramic substrate and possesses a smallest reported size of only 1 . 85 × 1 . 6 × 0 . 45 mm 3 $1.85\times 1.6\times 0.45\,{\mathrm{mm}}^{3}$ (that is , 0 . 061 × 0 . 053 × 0 . 015 λ g 3 $\mathrm{that}\mathrm{is},0.061\times 0.053\times 0.015\phantom{\rule{}{0ex}}{{{\lambda }}_{{g}}}^{3}$). The measured in‐band insertion loss (IL) is better than 1 . 47 dB $1.47\mathrm{dB}$ and a wide out‐of‐band suppression higher than 20 dB $20\,\mathrm{dB}$ upto 6 f 0 $6{f}_{0}$ are both achieved. Finally, comparison and discussion are implemented as well.