Islamabad, Pakistan
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Jawed S.A.,Institute of Applied Technologies | Cattin D.,University of Padua | Massari N.,Fondazione Bruno Kessler | Gottardi M.,Fondazione Bruno Kessler | Baschirotto A.,University of Salento
Analog Integrated Circuits and Signal Processing | Year: 2011

A single-package digital MEMS Capacitive Microphone (MCM) system is presented. The system consists of a MCM, which is wire-bonded with its readout interface (RI). The MCM sensor is fabricated using a combination of surface and bulk micromachining, employing diaphragm-stiffening to achieve piston-like diaphragm-movement and attaining required sensitivity with a smaller diaphragm-area. The RI is designed in 0.35 μm CMOS and it consists of a preamplifier (PAMP), a sigma-delta modulator (SDM), integrated biasing and digital control, converting the MCM capacitive variations into a single-bit over-sampled digital bitstream. The PAMP employs a two-terminal bootstrapped source-follower buffer to make the readout insensitive to the MCM parasitics, subsequently feeding a third-order single-loop single-bit modulator running at 2.5 MHz. The electrical measurements of the standalone RI demonstrate 55 dB A-weighted @ 1 Pa SNDR at the analog PAMP output and 80 dB A-weighted dynamic-range at the digital output, which corresponds to a conversion range from 40 to 120 dB SPL. The SNDR for acoustic measurements is 33 dB A-weighted @ 1 Pa, limited by the higher MCM thermal noise floor and reduced sensitivity (-53 dB V @ 1 Pa). The frequency characterization of the system for the complete audio-band demonstrates the effect of the system package towards higher frequencies (>9 kHz), giving rise to Helmholtz resonance, and reduction in sensitivity for low-frequencies (<400 Hz) because of acoustic short-circuiting inside the MCM due to flow-by slots. The complete system consumes 460 μA of total current for a 1.8 V single-supply. The total system dimensions are 4.5 × 2 mm 2 (excluding the package), demonstrating the viability of a low-area, low-power and high dynamic-range implementation of digital MCM. © 2011 Springer Science+Business Media, LLC.

Jawed S.A.,Institute of Applied Technologies | Qureshi J.A.,Institute of Applied Technologies | Ahmed M.,Institute of Applied Technologies | Shafique A.,Institute of Applied Technologies | And 3 more authors.
Analog Integrated Circuits and Signal Processing | Year: 2012

This paper presents a low-noise and high dynamic-range CMOS readout-IC (ROIC) for a 64 × 64 array of opto-electrical sensors. The readout chain comprises a pixel preamplifier array, correlated-double-sampling based switched-capacitor gain blocks, class-AB output buffer for driving off-chip loads and a 12-bit pipeline ADC for on-chip digitization. The pixel preamplifiers array, occupying an area of 30 μm × 30 μm per pixel, can either be hybridized to a separate IR or UV sensor or can be used as monolithic visible-light active CMOS pixel-array after exposing (by etching the pad) the embedded photodiode under the bonding pads. The ROIC is designed and fabricated in 0.25 μm 1P/5 M CMOS technology with 5 mm × 5 mm of total dimensions. The integrated readout chain, in integrate-then-read mode, demonstrates a dynamic range of 72 dB for electrically emulated sensor currents from 25 pA to 100 nA. It can support a frame rate of 700 fps, with single fully-differential analog as well as 12-bit digital output, at 10 MHz while consuming 17 mW with on-chip biases. © 2012 Springer Science+Business Media, LLC.

Arsalan Jawed S.,Institute of Applied Technologies | Qureshi W.A.,Institute of Applied Technologies | Shafique A.,Institute of Applied Technologies | Qureshi J.A.,Institute of Applied Technologies | And 2 more authors.
Microelectronics Journal | Year: 2013

This paper proposes six different CMOS-based temperature sensor topologies by exploiting temperature dependence of MOSFET's threshold voltage V T, the carrier's 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 0.37-1.83 mV/°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 0.25 μm TSMC 1P/5M process and are embedded in a 5 mm×5 mm 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. © 2012 Elsevier Ltd. All rights reserved.

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