Miniaturized Lumped Coupler with Low Frequency Signals Suppression

A miniaturized low temperature co-fired ceramic (LTCC) coupler using lumped-elements with low frequency signals suppression is fabricated and verified. The proposed structure achieved significant circuit size reduction using 3D spiral inductors and vertical interdigital capacitors (VICs). The overall size of the coupler is only 8 × 8 × 1 mm. Electromagnetic (EM) - simulated S
₁₁
, S
₂₁
, S
₃₁
and S
₄₁
are better than -26, -2.7, -3.1 and -26 dB at 200 MHz, respectively. Moreover, 40 dB suppression at the half center frequency (50 MHz) is obtained.