Three-dimensional millimeter-wave frequency-shift-based CMOS biosensor using vertically stacked LC oscillators

Abstract

This paper proposes a novel millimeter-wave frequency-shift-based CMOS biosensor capable of providing three-dimensional (3D) resolution. Using vertically stacked LC oscillators, the vertical resolution from the sensor chip surface can be obtained, which enables 3D target detection. Since the shifts in the frequencies of the upper and lower LC oscillators are different because of the changes in the complex dielectric constant of the target, the target can be detected in 3D. To verify the effectiveness of the proposed approach, a test chip was fabricated using a 65 nm CMOS process. The measurement results showed differences in the resonance frequency shifts of the upper and lower LC oscillators, which highlighted the capability of the proposed biosensor to provide 3D resolution.