Miniaturized On-Chip Notch Filter With Sharp Selectivity and >35-dB Attenuation in 0.13-μm Bulk CMOS Technology

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-
$\mu \text{m}$
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
²
(
${0.096}\times {0.296}$
mm
$^{{2}}$
).