Syed Arsalan Jawed

A 100

An ultra-low power 128 times 64 pixels vision sensor is here presented, featuring pixel-level spatial contrast extraction and binarization. The asynchronous readout only dispatches the addresses of the asserted pixels in bursts of 80 MB/s, significantly reducing the amount of data at the output. The pixel-embedded binary frame buffer allows the sensor to directly process visual information, such as motion and background subtraction, which are the most useful filters in machine vision applications. The presented sensor consumes less than 100 muW at 50 fps with 25% of pixel activity. Power consumption can be further reduced down to about 30 muW by operating the sensor in Idle-Mode, thus minimizing the sensor activity at the ouput.

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A CMOS interface for a piston-type MEMS capacitive microphone is presented. It performs a capacitance-to-voltage conversion by bootstrapping the sensor through a voltage pre-amplifier, feeding a third-order sigma-delta modulator. The bootstrapping performs active parasitic compensation, improving the readout sensitivity by ~12 dB. The total current consumption is 460 uA at 1.8 V-supply. The digital output achieves 80 dBA-DR, with 63 dBA peak-SNR, using 0.35 um 2P/4M CMOS technology. The paper includes electrical and acoustic measurement results for the interface.

W 128

A 641times128-pixel vision sensor, whose pixels estimate and perform a 1b quantization on the local contrast with a low energy budget is presented in this paper. The pixel-embedded time-adaptive visual processing is based on a charge-transfer mechanism, featuring no DC power consumption. The asynchronous readout process takes 147 mus and dispatches the column address of each asserted pixel, significantly reducing the chip activity at the interface. For typical indoor visual contrast estimation, involving 5% of the total number of pixels, the sensor exhibits a power consumption of 100 muW at 3.3V and 50 frames/s.

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A switched capacitor (SC) interface for a capacitive MEMS microphone is described in this paper. By properly switching the sensor, parasitic insensitive ac-coupling readout is directly performed without the need of a large bias resistor. The SC readout-circuit offers the advantages of a differential-topology for a single-ended sensor without accurate capacitor matching techniques

64 Pixels Contrast-Based Asynchronous Binary Vision Sensor for Sensor Networks Applications

A multi-function two-stage chopper-stabilized preamplifier (PAMP) for MEMS capacitive microphones (MCM) is presented. The PAMP integrates digitally controllable gain, high-pass filtering and offset control, adding flexibility to the front-end readout of MCMs. The first stage of the PAMP consists of a source-follower (SF) while the second-stage is a capacitive gain stage. The second-stage employs chopper-stabilization (CHS), while SF buffer shields the MCM sensor from the switching spurs. The PAMP uses MW poly bias resistors for the second-stage, exploiting Miller effect to achieve flat audio-band response. The gain and high-pass filtering corner can be adjusted by digitally controlling the capacitor banks in the PAMP. The offset-control feature of the PAMP is implemented using a narrow-band low-pass gm-C filter. The PAMP occupies 950µm × 950µm in 0.35µm CMOS technology and draws a 50µA total current from a 1.8V single supply. The PAMP achieves SNDR of 44dBA/Pa (elec. meas.) and 27dBA/Pa (acoustic meas.) and a conversion range from 50dBSPL to 120dBSPL.

A 828μW 1.8V 80dB dynamic-range readout interface for a MEMS capacitive microphone

This paper proposes six different CMOS-based temperature sensor topologies by exploiting temperature dependence of MOSFETs threshold voltage VT, the carriers mobility µ and the resistivity of n-well resistors. The proposed temperature sensors are designed for a wide temperature range of -100?C to +120?C and exhibit resolutions in the range of 0.04-0.448?C along with readout sensitivities in the range of 0.37-1.83mV/?C. For accuracy enhancement, automated single-point calibration is implemented for all topologies in conjunction with an off-chip reference temperature sensor. These calibrated temperature sensors exhibit measured inaccuracies between 0.2?C and 1?C for the proposed temperature range. These temperature sensors are designed in 0.25µm TSMC 1P/5M process and are embedded in a 5mmi?5mm imaging array readout IC to develop the thermal profile of the IC. The presented temperature sensors exhibit comparable performance metrics to state-of-the-art topologies in the literature with added advantage of a buffered output, which could be useful in case of a fast load drive and settling to implement faster control systems.

A 100μW 64×128-Pixel Contrast-Based Asynchronous Binary Vision Sensor for Wireless Sensor Networks

A low-power interface for readout and motion-control of a MEMS capacitive sensor is presented. The interface consists of a hybrid third-order sigma-delta modulator. The interface enhances the linearity and stability of the sensor by applying force feedback through bias voltage modulation. The modulator employs a hybrid, continuous + discrete-time topology, to reduce power consumption by avoiding a separate pre-amplifier for the sensor. Power consumption in the modulator is further reduced by an op-amp sharing scheme. The interface is designed in 0.35 um CMOS technology and is simulated in Cadence-Spectre. Simulation results are shown for a MEMS capacitive microphone.

A Switched Capacitor Interface for a Capacitive Microphone

This paper presents a low-power CMOS interface for a MEMS capacitive sensor. The interface has embedded force-balancing capability which improves the linearity of the readout for higher sound pressures. The interface also features a bias-charge control functionality to enhance the sensitivity of the microphone. The interface employs boot-strapped preamplifier for active parasitic capacitance compensation, followed by a 3rd-order sigma-delta modulator. The interface is designed in 0.35um CMOS technology and its brief simulation results in Cadence-Spectre are presented.

A multifunction low-power preamplifier for MEMS capacitive microphones

A new type of asynchronous time-based digital camera is here presented. The sensor architecture is characterized by a new analog low-power winner take all (WTA) network shared among all the pixels of the array. This circuit detects the most illuminated pixel and transmits it through the channel by queuing the other competitors. An iterative algorithm allows to read-out the entire array, temporally dispatching the information by means of an asynchronous read-out circuit placed at column and row level. The pixel, designed with a 0.35 mum CMOS technology and consisting of 28 transistors, performs a simulated average power consumption less than 10 nW @ 1.8 V for an impinging light power of 100 muW/cm2.

Low-power area-efficient wide-range robust CMOS temperature sensors

A novel algorithm for high intra-scene dynamic-range images representation is here proposed, which is based on Address Event Representation (AER) visual data. The values of the spiking pixels coming from the sensor are dynamically mapped into an 8-bit output, providing a real-time equalization of the scene. The algorithm has been tested using an AER emulator, based on a time-to-first spike imager. The simple implementation of the proposed technique makes it particularly suitable for AER sensors, turning into a real time processing and large programmability on the output tone mapping.