Miniaturized lumped‐element low‐temperature co‐fired ceramic balun using capacitance‐enhanced capacitors

Abstract

SummaryA capacitance‐enhanced capacitor (CEC) is proposed and applied to build a low‐temperature co‐fired ceramic (LTCC) balun for miniaturization. The capacitance enhancement is by adding horizontal fingers to traditional vertically interdigital capacitor (VIC) for capacitance increasing without size enlargement. The proposed CEC increased 7.2% capacitance comparing with that of traditional VIC. The balun using the proposed CEC is only 9.5 × 8.4 × 1 mm3, which is equivalent to 0.0034 × 0.0031 × 0.0004 λg3. The measured inband S11, S21, and S31 are better than −15, −3.6, and 3.5 dB from 46 to 58 MHz, respectively. A wide fractional bandwidth (FBW) of 24% based on 15 dB return loss is also reached. The proposed balun has widely applications in maritime navigation, aircraft navigation, and 1–1.5 Tesla (T) magnetic resonance imaging (MRI) applications.