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This work presents a multichannel electronic nose system that enables a range of novel applications owing to high sensitivity, low form factor and low power consumption. Each channel is based on a combination of doubly-clamped piezoelectric MEMS resonators and CMOS oscillator-based readout designed in TSMC 0.25 μm technology. Using "application specific" polymer coatings, the individual resonators can be tuned to detect mixtures of volatile organic compounds (VOCs). This system achieves ppm-level theoretical limit of detection for ethanol which paves the way towards a broad range of applications such as personalized health and environment air quality.

This paper describes the architecture and implementation of a novel voltage controlled oscillator based analogto-digital converter (VCO-ADC). Instead of a ring oscillator (RO), the VCO is built with a pulse frequency modulation (PFM) architecture where an analog feedback loop ensures both oscillation and linearity of the voltage-to-frequency conversion. A multibit first-order noise-shaped output is achieved by sampling a digital delay line that acts as a part of the oscillator and as a multibit quantizer. A prototype has been implemented in a 40nm CMOS process. Although most of the circuit elements are taken from a standard digital library, a transconductor is required as input stage. To ensure proper linearity, a bulk-driven transconductor has been designed. The ADC measurements reach 53 dB of SNDR at 1 GHz sampling frequency in a 20 MHz bandwidth with a pseudo-differential architecture. Powered at 1.1 V, the power consumption is 3.5 mW. The active area is 0.08 mm 2 . The resulting FoM equals 242 fJ/step.