A compact third-order 5 GHz bandpass filter with enhanced stopband characteristics in ultra thin organic substrate

A lumped-element bandpass filter based on new RXP ultra-thin organic technology with enhanced stopband rejections is proposed in this paper. The design is based on a third-order capacitively-coupled resonator circuit with unique resonator and ground inductor. For demonstration of the proposed circuit and RXP technology, a 5 GHz bandpass filter has been implemented in a four-metal layer 0.191 mm thin RXP substrate. The measured results have a good agreement with the simulation and show that insertion loss is less than 1.24 dB with larger than 1 GHz bandwidth and sharp rejections at both low and high stopband.