Miniaturized lumped-element LTCC quadrature hybrid with harmonics suppression

A compact lumped-element low temperature co-fired ceramic (LTCC) quadrature hybrid with harmonics suppression is proposed. The proposed topology enables significant circuit size reduction using spiral inductors with orthogonal input/output ports and vertical interdigital capacitors (VICs) placed in center of the hybrid. The overall size of the LTCC hybrid is only 11 × 11 × 1 mm. Electromagnetic (EM) — simulated S
11
, S
21
, S
31
and S
41
are better than −25, −2.8, −3.9 and −25 dB at 130 MHz, respectively. And the phase balance between the coupled and direct ports is 89.9° at 130 MHz. Moreover, 24 dB suppression for the second harmonic and 36 dB suppression for the third harmonic are obtained.