Admittance‐inverter‐based two‐section filtering power divider with OVER 40‐dB output isolation

Abstract

An admittance‐inverter‐based two‐section topology is proposed for filtering power dividers in this article aiming at high and wideband output isolation. Different from the classic two‐section Wilkinson power dividers, the bulky quarter‐wave transmission lines are removed and replaced by using two pairs of admittance inverters, which are realized by the input external quality factor (Qe‐in) and coupling coefficient (k12), respectively. Since the electric size of these coupling effects (Qe‐in and k12) are negligible, a significant size reduction is easily realized. In addition, two isolation elements are added between the input resonators and the output ones, respectively. Two‐prefect absorption points are accordingly realized in |S23|, indicating wider and higher output isolation compared with the reported designs using one isolation element. For demonstration, one two‐section filtering power divider is designed and fabricated. The circuit size is only 0.009λg2, while the output isolation exceeds 41.5 dB over the passband.