Charge-coupled-device digital-analogue convertor

A charge-coupled device (c.c.d.) digital-analogue convertor has been constructed, which is seen to have applications in the digital control of larger c.c.d. analogue processing systems.     

A single-chip video ghost canceller

A 450 K-transistor video ghost canceller chip, which implements a flexibly configurable IIR and FIR filter, is described. A very compact digital filter tap operating at a pixel rate of 14.32 MHz (4×F _sc) allows 180 programmable taps to be implemented in a die area of 56.25 mm² in a 1 μm TLM CMOS process. The device operates with 3.3- or 5-V power supplies     

ZOGMOST: an improved m.o.s.t. for c.c.d. peripheral circuits

An improved formation for m.o.s. transistors fabricated with the `shadow-etch? c.c.d. process is reported. The narrow self-aligned gaps produced by the process are used to provide an additional screen gate, which allows the gate-drain overlap capacitance to be minimised, thereby improving the frequency characteristics of linear and digital m.o.s. circuits. Depending on the gain of the stage involved, an improvement in the frequency performance of up to 5 times is expected, and practical results for the modified m.o.s.t. agree with this prediction.     

A Power-Efficient 5.6-GHz Process-Compensated CMOS Frequency Divider

This brief presents a robust, power efficient CMOS frequency divider for the 5-GHz UNII band. The divider operates as a voltage controlled ring oscillator with the output frequency modulated by the switching of the input transmission gate. The divider, designed in a 0.25-mum SOS-CMOS technology, occupies 35times25 mum² and exhibit a operating frequency of 5.6 GHz while consuming 79 muW at a supply voltage of 0.8 V. Process and temperature tolerant operation can be achieved by utilizing a novel compensation circuitry to calibrate the speed of the ring oscillator-based divider. The simple compensation circuitry contains low-speed digital logic and dissipates minimal additional power since it is powered on only during the one-time factory calibration sequence     

A high-speed wireless LAN

WLAN systems face technical problems similar to those encountered in outdoor wide-area radio-based systems, including the limited available bandwidth and fading noise due to multipath interference and blockage. The goal in WLAN system design is to transmit at the maximum information rate with an acceptable probability of error and minimum equipment complexity, power, and cost. Competing approaches use either infrared radiation or radio waves in the microwave or millimeter-wave bands. We have developed a radio solution at millimeter-wavelength frequencies, where the spectrum is sufficient to accommodate link speeds of hundreds of Mbps. Using a test bed with burst-mode transmission capability and an experimental 40-GHz radio, we have demonstrated a picocellular approach with a range of approximately 10 meters and link rates up to 185 Mbps. In addition, we have built a prototype modem with a raw link rate of 54 Mbps for use in a high-speed indoor WLAN demonstrator     

VLSI for OFDM

This article discusses the VLSI implications of high-speed coded orthogonal frequency-division multiplexing modulation. This is achieved by looking at practical examples of the computational blocks that constitute a COFDM modem and then examining examples of COFDM chips     

350 MHz opamp-RC filter in 0.18 μm CMOS

A 350 MHz fifth-order elliptic opamp-RC filter demonstrates that opamp-based filters need not have bandwidth disadvantages compared to transconductor-based filters. The filter, fabricated in standard digital 0.18 μm CMOS with 1.8 V V_DD, achieves 0.5 Vp-p signal swing at -40 dB THD     

Hydroquinone Is Not A Phagostimulant For The Formosan Subterranean Termite

It has been suggested that hydroquinone found in the labial glands of a number of termite species acts as a primary phagostimulating factor. We tested hydroquinone as a phagostimulant using workers from three colonies of the Formosan subterranean termite, Coptotermes formosanus, under both laboratory and field conditions. Hydroquinone at concentrations ranging from ca. 0.002–20.0 ng/cm² did not increase visitation by C. formosanus workers to treated over control filter papers, and was actually repellent at a 20 ng/cm² dose. No phagostimulant response to hydroquinone was observed in two colonies. In the third, there was a significant increase in feeding on filter paper treated with a 2 ng/cm² dose, but was significantly lower at a 20 ng/cm² dose. Furthermore, sand treated with a gradient of hydroquinone, did not evoke increased tunneling activity compared with controls. GC-MS analysis of C. formosanus workers indicated that hydroquinone was present at an average of 41 pg/worker. It was also determined that within one week about 11%hydroquinone in aqueous solution oxidized to 1,4-benzoquinone. Our findings indicate that hydroquinone alone does not act as a phagostimulant but instead may act as a repellent at higher concentrations. The attractant/arrestant of the Formosan termite may have multiple components of which hydroquinone, at low doses, could be one.     

A 66-MHz DSP-augmented RAMDAC for smooth-shaded graphicapplications

A fundamentally new type of RAMDAC is described in which a custom digital signal processor (DSP) is interposed between the RAM and the DAC. The device provides pseudoincreased resolution and increased color range by means of real-time mixing of any two colors contained in the color palette. This feature allows color images to be displayed without the familiar jagged edges; the ability to represent continuous edges yields the name continuous edge graphics (CEG) RAMDAC. Instead of all pixel values representing pointers to colors, 32 now represent a ratio between colors. The device allows mixing between any of the remaining 223 colors in amounts that depend on which ratio is used. This drastically increases the number of colors that an 8-b frame buffer can represent from 256 to over 700000. The device, containing 60000 devices, is fabricated in a 1.2-μm CMOS process supporting a 15-ns cycle operation