关键词: 3 dB电桥, LTCC, 低频, 宽边耦合

Abstract: The 3 dB bridge is widely used in communication systems for microwave signal synthesis and distribution. To meet demands for miniaturization and low-frequency applications, a low-frequency and compact bridge was developed using low-temperature co-fired ceramic technology. 3 dB coupling is achieved by a broadside coupling structure, with the standing wave ratio and isolation balanced by line width adjustments. Miniaturization is accomplished through spiral and 3D wire-winding structures. A coupled line-to-ground structure is introduced to further lower the operating frequency. The device is packaged in a standard 1206 package. Measured results demonstrate good agreement with simulations, exhibiting a passband from 330 MHz to 580 MHz, with an insertion loss of ≤1.3 dB, a standing wave ratio of ≤1.5, an isolation of ≥17.9 dB, an amplitude imbalance of ≤1.2 dB, and a phase imbalance of ≤5°.

Key words: 3 dB bridge, LTCC, low frequency, broadside coupling structure