Compact LTCC Branch-line Coupler with Harmonics Suppression

Abstract

A compact branch-line coupler with a wide stopband and harmonic suppression is proposed using low temperature co-fired ceramic (LTCC) packaging technique. The 3D spiral inductors and vertically-interdigital capacitors (VICs) are utilized for a high-level integration and the entire size reduction. EM-simulated S <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</inf> , S <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</inf> , S <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">31</inf> and S <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">41</inf> of the proposed coupler are better than -28, -3.3, -3.2 and -28 dB at 100 MHz, respectively. Simulated phase difference between coupling and through ports is 91°±2°at the working bandwidth. Moreover, 40 dB suppression of 2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">nd</sup> -order harmonic is obtained.