4,466 research outputs found
CMOS low voltage preamplifier based on 1/F noise cancellation
Noise in CMOS integrated circuits -- Noise sources in MOSFET transistors- -- Low noise techniques -- Chopper stabilization technique -- A CHS behavior model in MATLAB/SIMULINK -- Supplemental analysis of CHS -- Low voltage operation & elementary circuits -- Voltage requirements of analog circuits -- Basic circuits and functions -- Implementation of the CHS modules -- Noise in cascaded stages -- Modulators -- Selective amplifier -- Automatic tuning & machine oscillator -- Simulation results and experimental prototype
A 0.35 μm CMOS 17-bit@40-kS/s cascade 2-1 ΣΔ modulator with programmable gain and programmable chopper stabilization
This paper describes a 0.35μm CMOS chopper-stabilized Switched-Capacitor 2-1 cascade ΣDelta; modulator for automotive sensor interfaces. For a better fitting to the characteristics of different sensor outputs, the modulator includes a programmable set of gains (x0.5, x1, x2, and x4) and a programmable set of chopper frequencies (fs/16, fs/8, fs/4 and fs/2). It has also been designed to operate within the restrictive environmental conditions of automotive electronics (-40°C, 175°C). The modulator architecture has been selected after an exhaustive comparison among multiple ΣΔM topologies in terms of resolution, speed and power dissipation. The design of the modulator building blocks is based upon a top-down CAD methodology which combines simulation and statistical optimization at different levels of the modulator hierarchy. The circuit is clocked at 5.12MHz and consumes, all together, 14.7mW from a single 3.3-V supply. Experimental measurements result in 99.77dB of Dynamic Range (DR), which combined with the gain programmability leads to an overall DR of 112dB. This puts the presented design beyond the state-of-the-art according with the existing bibliography
Magnetoresistive biosensors with on-chip pulsed excitation and magnetic correlated double sampling.
Giant magnetoresistive (GMR) sensors have been shown to be among the most sensitive biosensors reported. While high-density and scalable sensor arrays are desirable for achieving multiplex detection, scalability remains challenging because of long data acquisition time using conventional readout methods. In this paper, we present a scalable magnetoresistive biosensor array with an on-chip magnetic field generator and a high-speed data acquisition method. The on-chip field generators enable magnetic correlated double sampling (MCDS) and global chopper stabilization to suppress 1/f noise and offset. A measurement with the proposed system takes only 20 ms, approximately 50× faster than conventional frequency domain analysis. A corresponding time domain temperature correction technique is also presented and shown to be able to remove temperature dependence from the measured signal without extra measurements or reference sensors. Measurements demonstrate detection of magnetic nanoparticles (MNPs) at a signal level as low as 6.92 ppm. The small form factor enables the proposed platform to be portable as well as having high sensitivity and rapid readout, desirable features for next generation diagnostic systems, especially in point-of-care (POC) settings
Progress of analog-hybrid computation
Review of fast analog/hybrid computer systems, integrated operational amplifiers, electronic mode-control switches, digital attenuators, and packaging technique
Spacelab simulation using a Lear Jet aircraft: Mission no. 4 (ASSESS program)
The fourth ASSESS Spacelab simulation mission utilizing a Lear Jet aircraft featured trained experiment operators (EOs) in place of the participating scientists, to simulate the role and functions of payload specialists in Spacelab who may conduct experiments developed by other scientists. The experiment was a broadband infrared photometer coupled to a 30-cm, open port, IR telescope. No compromises in equipment design or target selection were made to simplify operator tasks; the science goals of the mission were selected to advance the mainline research program of the principle investigator (PI). Training of the EOs was the responsibility of the PI team and consisted of laboratory sessions, on-site training during experiment integration, and integrated mission training using the aircraft as a high-fidelity simulator. The EO permission experience in these several disciplines proved adequate for normal experiment operations, but marginal for the identification and remedy of equipment malfunctions. During the mission, the PI utilized a TV communication system to assist the EOs to overcome equipment difficulties; both science and operations were successfully implemented
Device modelling for bendable piezoelectric FET-based touch sensing system
Flexible electronics is rapidly evolving towards
devices and circuits to enable numerous new applications. The
high-performance, in terms of response speed, uniformity and
reliability, remains a sticking point. The potential solutions for
high-performance related challenges bring us back to the timetested
silicon based electronics. However, the changes in the
response of silicon based devices due to bending related stresses is
a concern, especially because there are no suitable models to
predict this behavior. This also makes the circuit design a
difficult task. This paper reports advances in this direction,
through our research on bendable Piezoelectric Oxide
Semiconductor Field Effect Transistor (POSFET) based touch
sensors. The analytical model of POSFET, complimented with
Verilog-A model, is presented to describe the device behavior
under normal force in planar and stressed conditions. Further,
dynamic readout circuit compensation of POSFET devices have
been analyzed and compared with similar arrangement to reduce
the piezoresistive effect under tensile and compressive stresses.
This approach introduces a first step towards the systematic
modeling of stress induced changes in device response. This
systematic study will help realize high-performance bendable
microsystems with integrated sensors and readout circuitry on
ultra-thin chips (UTCs) needed in various applications, in
particular, the electronic skin (e-skin)
On chopper effects in discrete-time ΣΔ modulators
Analog-to-digital converters based on ΣΔ modulators are used in a wide variety of applications. Due to their inherent monotonous behavior, high linearity, and large dynamic range, they are often the preferred option for sensor and instrumentation. Offset and flicker noise are usual concerns for this type of applications, and one way to minimize their effects is to use a chopper in the front-end integrator of the modulator. Due to its simple operation principle, the action of the chopper in the integrator is often overlooked. In this paper, we provide an analytical study of the static effects in ΣΔ modulators, which shows that the introduction of chopper is not transparent to the modulator operation and should thus be designed with care.This work has been partially funded by the Spanish Government project TEC-2007-68072 and the CSIC project 200850I213.Peer reviewe
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