Miniaturized On-Chip Notch Filter With Sharp Selectivity and >35-dB Attenuation in 0.13-μm Bulk CMOS Technology
Lisheng Chen, He Zhu, Roberto Gómez‐García, Xi Zhu
Abstract
In this letter, a compact electromagnetic (EM) structure for miniaturized notch filter design in standard silicon technology is presented. Unlike prior-art on-chip bandstop filters, this filter configuration achieves sharp selectivity and large notch attenuation depth by producing a strong coupling between the top layer (i.e., resonating stub-loaded input-to-output direct path) and the bottom layer (i.e., two spiral-line grounded resonators). Moreover, as these vertically-stacked layers are broadside coupled, the physical footprint of the EM structure is significantly reduced. To demonstrate the proposed principle of notch filter, a simplified lossless behavioral model using ideal lumped elements is developed and verified. In addition, EM simulations are performed for parametric studies. As proof of concept, a prototype is fabricated in 0.13- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> bulk CMOS technology. The measurement results show that the designed filter exhibits a notch located at 19 GHz with an attenuation depth higher than 37 dB. The footprint, excluding the pads, is only 0.028 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${0.096}\times {0.296}$ </tex-math></inline-formula> mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{{2}}$ </tex-math></inline-formula> ).