Miniaturized Ultra-Wideband Bandpass Filter With Ultra-Wide Stopband Using π-Type Unit With Inductive Loading on Integrated Passive Device
Baoguang Liu, Yujin Zhou, Chonghu Cheng
Abstract
In this brief, a new miniaturized ultra-wideband (UWB) bandpass filter (BPF) with ultra-wide stopband (UWS) using <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pi $ </tex-math></inline-formula> -type unit with inductive loading on integrated passive device (IPD) is proposed. the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pi $ </tex-math></inline-formula> -type with non-periodic response is equivalent to the coupled line with open-ends diagonally for the first time. The proposed compact lumped BPF based on three <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pi $ </tex-math></inline-formula> -type units is not only easy to design UWB response without strong coupling, but also has the advantage of the UWS due to the non-periodic phase of the unit. Besides, the high frequency selectivity can be obtained for two transmission zeros near the passband. In final, a prototype with 3-dB fractional bandwidth of 111% is designed and fabricated at 4 GHz ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${f} _{0}$ </tex-math></inline-formula> ). The upper-stopband attenuation higher than 24 dB is extended to more than 45 GHz ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$> 11.25{f} _{0}$ </tex-math></inline-formula> ). It occupies only 0.008 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{0} \times 0.032\,\,\lambda _{0}$ </tex-math></inline-formula> , where <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{0}$ </tex-math></inline-formula> is the free-space wavelength at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${f} _{0}$ </tex-math></inline-formula> .