A low-noise low-power cmos interface for a GMR biosensor application

The thriving demand in the need of early disease detection of modern medicine dictates an effective and cheap bio-detection system for organic samples. The enzymatic, nuclear or fluorescent labeling approaches have proven inefficient and expensive to realize. Recent developments in magnetic nanotechnologies have shown serious potential for biomolecular detection by labeling the organic molecules with appropriate magnetic nanotags. For sensing those nanotags, giant magnetoresistive spin-valve (GMR SV) sensors possess great promise for sensitive biosensing applications. This project proposes an CMOS (UMC 0.18 um technology) interface for a specific ultra sensitive (<100nT) GMR SV sensing element, which consumes low power and amplifies the low level noisy sensor signal without adding additional noise, then converts the signal to digital data. Each design step has been described with necessary trade-offs and the selections. The theory behid the GMR SV sensor and magnetic nanobeads, the selection and the modeling of the sensing element are also covered. The performance evaluation of each block-sub-block and main block is given with simulation results.