Microcantilever-based biosensors are a promising tool to detect biomolecular interactions in a direct way with high accuracy. We show the development of a portable biosensor microsystem able to detect nucleic acid hybridization with high sensitivity. The microsystem comprises an array of 20 micromechanical cantilevers produced in silicon technology, a polymer microfluidic system for delivery of the samples, an array of 20 vertical cavity surface emitting lasers (VCSELs) with collimated beams thanks to an integrated microlens array, an optical coupling element to provide the optical path required, and chips with the photodetectors and the CMOS circuitry for signal acquisition and conditioning, capable of measuring the cantilever deflection with sub-nanometer resolution. Robust immobilization and regeneration procedures have been implemented for the oligonucleotide receptor sequences. In a further innovation, an optical waveguide cantilever transducer has been also developed in order to improve the final performance of the device. This has a number of advantages in terms of a simple optical geometry and improved sensitivity.
Abstract-This paper presents a low-cost digital technique for background calibration of comparator offsets in Pipeline ADCs. Thanks to calibration, comparator offset errors above half the stage least-significant bit (LSB) margin in a unitary redundancy scheme are admissible, thus relaxing comparator design requirements and allowing their optimization for low-power highspeed applications and low input capacitance. The technique also makes it possible to relax design requirements of stage amplifiers within the Pipeline queue, since output swing and driving capability are significantly lower. In this brief, the proposal is validated using realistic hardware-behavioral models.
In this paper, the MOS transistor (MOST) moderate-weak inversion region is shown to be the optimum design zone for CMOS 2.4-GHz common-source low noise amplifiers (CS-LNA) focused on low power consumption applications. This statement is supported by a systematic study where the MOST is analyzed in all-inversion regions using an exhaustive CS-LNA noise figure-power consumption optimization technique with power gain constraint. Effects of bias choke resistance and MOST capacitances are carefully included in the study to obtain more accurate results, especially for the moderate-weak inversion region. Noise figure, power consumption and gain versus the inversion region are described with design space maps, providing the designer with a deep insight of their trade-offs. The Pareto-optimal design frontier obtained by calculation, -showing the moderate-weak inversion region as the optimum design zone-is re-verified by extensive electrical simulations of a high number of designs. Finally, one 90-nm 2.4-GHz CS-LNA Pareto optimal design is implemented. It achieves the best FoM considering under-mW CS-LNAs published designs, consuming 684 µW, a noise figure of 4.36 dB, a power gain of 9.7 dB and an IIP3 of -4 dBm with load and source resistances of 50 Ω.
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