A 0.1 mm$^{2}$ , Wide Bandwidth Continuous-Time $SigmaDelta$ ADC Based on a Time Encoding Quantizer in 0.13 $mu$ m CMOS

The ADC shown in this paper uses an innovative sigma-delta (SigmaDelta) architecture that replaces the flash quantizer and mismatch corrected DAC of a multibit continuous time (CT) modulator by a time domain encoder similar to a PWM modulator to reduce the effective ADC area. The modulator achieves the resolution of a multibit design using single bit circuitry by concentrating most of the quantization error energy around a single frequency, which is afterwards removed, seizing the zeros of a sinc decimation filter. The non flat error spectrum is accomplished by use of two filter loops, one of which is made to operate in a self-oscillating mode. An experimental CT-SigmaDelta ADC prototype has been fabricated in 0.13 mum CMOS which implements a third order modulator with two operating modes. Measurements show an effective number of bits (ENOB) of 10 bits and 12 bits in a signal bandwidth of 17 MHz and 6.4 MHz, respectively, and a power-efficient figure of merit (FoM = Pwr/2 middot BW middot 2^ENOB) of 0.48 pJ/conversion at 1.5 V supply. The active area of the ADC is 0.105 mm².     

A 85-dB dynamic range multibit delta-sigma ADC for ADSL-CO applications in 0.18-/spl mu/m CMOS

A high-resolution multibit sigma-delta analog-to-digital converter (ADC) implemented in a 0.18-/spl mu/m CMOS technology is introduced. The circuit is targeted for an asymmetrical digital subscriber line (ADSL) central-office (CO) application . An area- and power-efficient realization of a second-order single-loop 3-bit modulator with an oversampling ratio of 96 is presented. The /spl Sigma//spl Delta/ modulator features an 85-dB dynamic range over a 300-kHz signal bandwidth. The measured power consumption of the ADC core is only 15 mW. An innovative biasing circuitry is introduced for the switched-capacitor integrators.     

Multicomponent gas diffusion in hardened cement paste at temperatures up to 350 °C

Diffusional gas transport of a H₂/CO₂ mixture versus N₂ in the pore system of hardened cement pastes was studied at four temperatures up to 350 °C in a Wicke-Kallenbach cell. The pastes possessed separation factors α_H2,CO2 from 1.42 to 3.43, i.e. the diffusion of hydrogen took place considerably faster than the diffusion of carbon dioxide. The separation factors depended on the threshold radii of the pastes, smaller threshold radii leading to higher separation factors. The Knudsen numbers of the controlling constrictions of the pore system and the temperature dependence of the effective diffusion coefficients of the gases show that gas transport in these constrictions takes place in the transient regime between Knudsen diffusion and bulk diffusion, smaller constriction widths leading to predominating Knudsen diffusion. It is therefore possible to use cement paste membranes to separate gas components of low molecular weight from higher weight components.     

Postoperative sensitivity of vascular pedicles latissimus dorso transplant without neural anastomosis

It is still a matter of controversy whether anastomosis of the sensory nerves is necessary in free transplants of microvascular reanastomosed myocutaneous latissimus dorsi flaps in the oral cavity and oropharynx. Some surgeons perform this routinely because they expect fewer complications in skin with a sensory nerve supply. We clinically examined 30 patients in order to assess the sensory innervation of the transplant tissue. All patients received free transplants of microvascular reanastomosed latissimus dorsi flaps during a tumor operation in the oral cavity. Sensation was determined clinically according to pain, temperature, pressure, two point discrimination and vibration. In most patients sensation in the Latissimus dorsi flap does not return. These findings suggest that reinnervation in the myocutaneous latissimus dorsi flap mostly does not occur, indicating that there is a need for anastomosis of a sensory nerve during transplant surgery with a myocutaneous latissimus dorsi flap to reinnervate it.     

Sensate myocutaneous latissimus dorsi flap

A case using a sensate myocutaneous latissimus dorsi flap for oral defect reconstruction is reported. Preparation of the cutaneous branches of a latissimus dorsi autologous transfer and their subsequent anastomoses with sensitive nerves at the recipient site resulted in superficial and deep sensibility of the transfer, following a short rehabilitation period. As early as 4 months postoperatively, pain and pressure sensations could be evoked in the flap. Sharp and blunt discrimination and sense of vibration were found 6 months postoperatively. Nine months postoperatively, caloric differentiation could be elicited.