A miniaturized low-loss absorptive bandpass filter using IPD technology

In this article, a highly miniaturized absorptive bandpass filter based on a novel topology is presented. The filter topology utilizes a resistor-loaded network to achieve absorptive characteristics while additional capacitive coupling between series resonators is introduced to enhance selectivity. The proposed filter with a center frequency of 2.5 GHz and a 3-dB bandwidth of 2800 MHz is implemented using a GaAs integrated passive device (IPD) technology, exhibiting a small die size (0.7 mm×1.13 mm), low loss in-band insertion loss (0.9 dB), high out-of-band rejection (8.8f0¿25 dB), and a wide low-reflection frequency range. The measurement results show good agreement with the simulations. These features show promising applications in highly integrated RF systems.