Electronically switchable band tuned filtering power divider for Sub-6 GHz applications

This work presents a compact electronically switchable filtering power divider (FPD) for Sub-6 GHz wireless front ends requiring adaptive and spectrum-flexible RF hardware. Conventional multi-band receivers rely on separate narrowband and wideband chains, resulting in increased loss, complexity, and circuit footprint. To overcome these limitations, a miniaturized band-tuned FPD is developed by integrating a folded-resonator bandpass filter with a Wilkinson-based power-divider core through a coupled-line capacitive interface. The resonator employs inverted S-shaped and modified C-shaped elements to achieve size reduction, while four PIN diodes embedded in a step-impedance resonating structure enable electronic switching between wideband and narrowband modes. In the diode-OFF state, the proposed structure realizes wideband operation centered at 2.9 GHz with a 34.4% fractional bandwidth, insertion loss near 1.4 dB, return loss better than 15 dB, and isolation better than 10 dB. While for the diode-ON state, the circuit offers narrowband response centered at 2.35 GHz, realizing return loss better than 20 dB, isolation better than 10 dB, within an electrical size of only 0.14λ₀ × 0.18λ₀. The results confirm that the proposed FPD provides equal power division with high isolation, and electronically selectivity.