Miniaturized IPD Filter With Multiple Flexible Transmission Zeros and High Attenuation

Abstract

In this letter, a miniaturized integrated passive device (IPD) bandpass filter (BPF) with multiple flexibly controllable transmission zeros (TZs), high attenuation, and low loss is proposed. The proposed novel $\pi $ -type filtering unit incorporates dual LC series resonant circuits that allow precise placement of two TZs, enhancing the BPF’s selectivity and expanding the stopband bandwidth. Since the branches generating TZs are not the main energy paths, adding multiple TZs causes minimal loss. A three-stage BPF, based on this $\pi $ -type filtering unit, demonstrates high selectivity and attenuation by introducing three TZs on each side of the passband. At the same time, it possesses the advantage of low loss. Manufactured using the GaAs-based IPD technology, the filter exhibits excellent agreement between the simulated and measured results, showcasing its potential for applications requiring ultraminiaturization and high performance in wireless communication systems.