A new CMOS transconductor with wide transconductance tuning range and very low distortion is presented. The input stage features a highly linear conversion of the input voltage into current form. Electronically progra...
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A new CMOS transconductor with wide transconductance tuning range and very low distortion is presented. The input stage features a highly linear conversion of the input voltage into current form. Electronically programmable current mirrors able to operate in weak or moderate inversion provide a continuous transconductance tuning range of two decades without affecting the large input signal range available. Measurement results of a prototype fabricated in a 0.5/spl mu/m CMOS technology shows a THD of -66.5dB for a 100 kHz differential input of 2V/sub pp/.
A low-voltage CMOS class AB OTA with rail to rail input/output swing, low supply voltage and very high slew rate is presented. The scheme is based on a combination of floating gate transistors, local common-mode feedb...
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ISBN:
(纸本)0780387775
A low-voltage CMOS class AB OTA with rail to rail input/output swing, low supply voltage and very high slew rate is presented. The scheme is based on a combination of floating gate transistors, local common-mode feedback and class AB input. The proposed OTA does not suffer from typical reliability problems related with initial charge trapped in the floating gates devices. Simulation and experimental in 0.5 /spl mu/m CMOS technology verify the scheme operating with 1V dual supply and 1.9 Vp-p input and output swing.
We investigated the performance of an ordered-subsets expectation-maximization (OSEM) algorithm for accelerated reconstruction in cone-beam SPECT. SPECT scans were performed using a Defrise phantom filled with 0.9/spl...
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We investigated the performance of an ordered-subsets expectation-maximization (OSEM) algorithm for accelerated reconstruction in cone-beam SPECT. SPECT scans were performed using a Defrise phantom filled with 0.9/spl mu/Ci/ml of Tc-99m and a dual-head gamma camera equipped with one cone-beam (CBC, f=70 cm) and one parallel-beam collimator (PBC). Images were reconstructed using a fully-3D approach with resolution and attenuation modeling and an ordered-subsets version of a maximum-likelihood expectation-maximization algorithm (MLEM). Three grouping patterns of subsets were applied: consecutive, orthogonal, and uniform. In contrast to PBC SPECT, we observe that, in CBC SPECT, the reconstruction grouping pattern of the subsets is very important for the image quality obtained. Only when the projection data grouped into a subset were selected as uniformly as possible from all the acquired views, were the image quality and the noise in the images very close to results obtained using MLEM. However, we note that, for both CBC and PBC SPECT, the loglikelihood for a given iteration is practically the same for different grouping patterns of subsets.
This paper suggests that many of these challenges are direct result of the institutional dichotomy within the once vertically integrated industry. Namely, while the generation portion of this industry has made major p...
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This paper suggests that many of these challenges are direct result of the institutional dichotomy within the once vertically integrated industry. Namely, while the generation portion of this industry has made major progress toward becoming for profit, value-based industry, both the delivery (transmission) and the end user (distribution) remainders are left without any clear institutional support to adjust and provide their value to the end users in the changing industry. This paper shows that in order to move forward and provide some more natural ways of valuing generation, transmission, distribution and customers' willingness to respond to the changing system constraints, several issues must be resolved. Some possible institutional and technological approaches to solving the system reliability problems in the changing industry were introduced in this presentation.
When the process uncertainty size increases, even linear minimum phase systems must sacrifice desirable aggressive feedback control benefits to avoid an excessive 'cost of feedback', while preserving the robus...
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Tracking feedback control trade-offs increase dangerously with arbitrarily large uncertainties in the process mode!. This is shown by the bounds in the QFT domain. In this context, the paper develops a theory on the c...
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A novel technique for operating MOS translinear loops at very low supply voltages is presented. It is based on the use of a biasing cell recently reported and named "flipped voltage follower", that allows to...
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A novel technique for operating MOS translinear loops at very low supply voltages is presented. It is based on the use of a biasing cell recently reported and named "flipped voltage follower", that allows to create a very low impedance node in the translinear loops with a controllable and well-defined DC voltage even for large current swings, thus relaxing the supply voltage requirements for a given input current range. Measurement results of a 1.5V MOS translinear loop circuit implementing the square-root operator and fabricated in a 2.4/spl mu/m CMOS process confirm the viability of the proposed approach.
When the process uncertainty size increases, even linear minimum phase systems must sacrifice desirable aggressive feedback control benefits to avoid an excessive ‘cost of feedback’, while preserving the robust stab...
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When the process uncertainty size increases, even linear minimum phase systems must sacrifice desirable aggressive feedback control benefits to avoid an excessive ‘cost of feedback’, while preserving the robust stability. With a suitable uncertainty division and a QFT controller-prefilter to command each uncertainty subset inside a controller-scheduler structure, it is possible to enhance the feedback tracking performance without an excessive bandwidth. To preserve the robust stability from any failure in the switching, each controller is designed to be stable in the whole uncertainty domain, and as accurate in command tracking as desired in its uncertainty subset.
A novel design technique for closed-loop amplifier circuits, suited to very low supply voltages, is proposed. It is based on the use of quasi-floating gate MOS transistors, thus avoiding issues encountered in true flo...
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A novel design technique for closed-loop amplifier circuits, suited to very low supply voltages, is proposed. It is based on the use of quasi-floating gate MOS transistors, thus avoiding issues encountered in true floating-gate MOS structures such as initial floating gate charge and gain-bandwidth product degradation. A programmable-gain inverting amplifier, a digital to analog converter, and a sample and hold circuit, all based on this technique, are presented along with simulation results, thus illustrating the proposed approach.
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