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This paper presents an asynchronous SAR-assisted time-interleaved SAR (SATI-SAR) ADC as a suitable architecture in a low-supply-voltage condition. Settling-While-Conversion enabled by the Assist-ADC relaxes the DAC settling time requirement and makes it possible to insert a minimized capacitor shuffling logic with no speed penalty. A proposed gain-boosting dynamic pre-amplifier enhances the noise performance of the comparator and a self time-reference generation function is embedded in the pre-amplifier for a speed-enhanced asynchronous decision. A proposed dual-mode clock generator generates a low-jitter fixed-width sampling pulse for high-frequency operation while it generates a low-power-but-low-quality clock for low-frequency operation. With the dual-mode clock generator enabled, a prototype 65 nm CMOS 0.6 V 12 b 10 MS/s ADC achieves an ENOB of 10.4 at a Nyquist-rate input, and the peaks of DNL and INL are measured to be 0.24 LSB and 0.45 LSB, respectively. The FoM is 6.2 fJ/conversion-step with a power consumption of 83 µW. The ADC operates under the lowest supply voltage of 0.6 V among comparable designs with ENOBs over 10 and conversion rates over 1 MS/s. Index Terms-Asynchronous SAR ADC, gain-boosting dynamic comparator, low voltage, low-jitter clock, low-noise comparator, SAR-assisted time-interleaved SAR (SATI-SAR).

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A power-efficient and speed-enhancing technique for time-interleaved (TI) SAR ADCs that is assisted by a lowresolution flash ADC is presented. The 3 b MSBs achieved from a flash ADC at every clock save two decision cycles from every SAR ADC channel, resulting in a reduced number of time interleaving channels with a total 27% energy saving compared with the energy consumption of a conventional TI SAR ADC . A prototype 6 b 2 GS/s ADC in a 45 nm CMOS consumes 14.4 mW under a 1.2 V supply and achieves 5.2 ENOB Nyq with a background offset calibration.I. 978-1-4799-0280-4/13/$31.00 c 2013 IEEE

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Inspired by the human cochlea, we propose a directional sound sensor using a resonator array to overcome the limitations of existing directional microphones. The proposed sensor consists of multiple cantilevers that respond to different resonance frequencies and separately acquire signals to then combine them for sound sensing. The directionality of the cantilevers is bipolar (figure -of-8) because a signal proportional to the input sound's pressure gradient is generated. We adopt multimode resonance to cover the wide frequency range of 100-8,000 Hz using few resonators. A wide-bandwidth (low-quality-factor) trenched cantilever is used to obtain a flat frequency response. Bidirectional sound sensors are tapered to achieve acoustic beamforming by simple signal processing. The directional characteristics can be easily changed according to the weighted sum of the signals acquired from a pair of sensors. We demonstrate that ambient noise can be effectively suppressed through beamforming to acquire the desired signal using the proposed sensor.