A matched filter using charge coupled device for pulse-code modulation

A matched filter using CCD for PCM is made. The experimental results of output waveform, transfer function and output signal-to-noise ratio are given and compared with the theoretical ones. The output signal-to-noise ratio for the non-return-to-zero codes is 1 dB below the theoretical value.     

Root-law circuit using monolithic bipolar-transistor arrays

Close matching in the respective parameters of bipolar transistors fabricated on the same monolithic chip facilitates the design of a circuit characterised by where I0 is the output current, I1, ?, Im are input currents and n (?1) is an integral number. Experimental measurements for n=2, m=3 and 1 ?A ? Ir ? 1 mA are presented and discussed in relation to a simple theoretical error formula.     

Differential pulse-code modulation (PCM) with entropy coding

As the transmission rateRgets large, differential pulse-code modulation (PCM) when followed by entropy coding forms a source encoding system which performs within 1.53 dB of Shannon's rate distortion function which bounds the performance of any encoding system with a minimum mean-square error (mmse) fidelity criterion. This is true for any ergodic signal source. Furthermore, this source encoder introduces the same amount of uncertainty as the mmse encoder. The 1.53 dB difference between this encoder and the mmse encoder is perceptually so small that it would probably not be noticed by a human user of a high quality (signal-to-noise ratio(S/N) geq 30dB) speech or television source encoding system.     

A PCM voice codec with on-chip filters

Describes a monolithic NMOS coder/decoder (codec) with associated CCD transversal minimum phase filters which has been successfully implemented. The codec operates by charge redistribution in a binary-weighted capacitor array, with a resistor chain to define individual steps. The experimental performance compares well with PCM codecs implemented with discrete components.     

UAVs-based antenna arrays using time modulation

Telecommunication Systems - This paper applies time modulation to deal with the design of antenna arrays for UAVs formation flight using a rectangular micro-strip as antenna element in the...     

An all-MOS integrated delta modulation codec

A linear delta modulation (LDM) codec has been produced with a p-channel aluminum-gate MOS IC process technology. A distortion, which is produced by granular size fluctuation, is discussed. The conclusion is obtained that an MOS integrated LDM codec, which is applicable to voice communication purposes, can be produced.     

Detection and estimation in sensor arrays using weighted subspacefitting

The problem of signal parameter estimation of narrowband emitter signals impinging on an array of sensors is addressed. A multidimensional estimation procedure that applies to arbitrary array structures and signal correlation is proposed. The method is based on the recently introduced weighted subspace fitting (WSF) criterion and includes schemes for both detecting the number of sources and estimating the signal parameters. A Gauss-Newton-type method is presented for solving the multidimensional WSF and maximum-likelihood optimization problems. The global and local properties of the search procedure are investigated through computer simulations. Most methods require knowledge of the number of coherent/noncoherent signals present. A scheme for consistently estimating this is proposed based on an asymptotic analysis of the WSF cost function. The performance of the detection scheme is also investigated through simulations     

Flexible circuit and sensor arrays fabricated by monolithic silicon technology

A novel monolithic batch fabrication method produces arrays of silicon islands containing conventional integrated-circuit components and supported by a flexible polyimide substrate. Islands are interconnected by photolithographically defined gold leads embedded in the polyimide. Because no bonding pads are necessary at island boundaries, lead density between islands is at least twice that available using hybrid techniques. The technology has been used to fabricate thermohaeter arrays for temperature profile measurement during hypertherminal treatment of cancer. An array consists of 20 silicon islands; each island contains one p-n diode, which is used as a thermometer. These linear arrays are 1 mm wide by 0.4 mm thick, with 20-µm-wide by 1-µm-thick gold interconnects on 40-µm centers. The flexible array technology is currently being modified to fabricate two-dimensional arrays of micromechanical sensors for robotic and biomedical uses.     

Digital portable transceiver using GMSK modem and ADM codec

Digital mobile radio transmission techniques and integrated circuit devices have been developed for application to a digital portable transceiver utilizing narrow-band GMSK modulation and ADM voice coding. Design and performance of a quadrature type GMSK modulator and a single-chip coherent demodulator as the GMSK modem are described. To overcome slow fading, encountered in portable applications, switching diversity using a jitter detection type sensor is proposed and shown to be effective. An experimental portable transceiver, developed to demonstrate hardware feasibility, is also described.     

1.54 lm GaSb/AlGaSb multi-quantum-well monolithic laser at 77 K grown on miscut Si substrate using interfacial misfit arrays

A GaSb quantum-well (QW) laser diode grown monolithically on a 5deg miscut Si (001) substrate is presented. The III-Sb epi-structure is grown monolithically on the miscut Si substrate via a thin (50 nm) AlSb nucleation layer. The 13% lattice mismatch between AlSb and Si is accommodated by a self-assembled 2D array of interfacial misfit dislocations (IMF). The 5deg miscut geometry enables simultaneous IMF formation and anti-phase domain suppression. The 1 mm times 100 mum GaSb QW laser diode operates under pulsed conditions at 77 K with a threshold current density of 2 kA/cm² and a maximum peak power of ~20 mW. Furthermore, the device is characterised by a 9.1 Omega forward resistance and a leakage current density of 0.7 A/cm² at -5 V.     

Electromagnetic design aspects of packages for monolithic microwaveintegrated circuit-based arrays with integrated antenna elements

Reliable and cost-effective packaging of monolithic microwave integrated circuits (MMICs) is an important aspect of the design of phased array systems. At millimeter wavelengths, where small dimensions make machining and assembly a complex matter, the interconnections between the modules housing the MMIC components and the antenna elements are a source of unreliability as well as a potential problem in terms of electromagnetic losses. One solution involves the integration of antenna elements onto the MMIC chips. The paper addresses the issues involved in packaging and housing MMIC chips with integrated antenna elements and presents some insights into the electromagnetic design of such packages     

Millimeter wave monolithic high electron mobility (HEM) varactor diode-grid frequency tripler arrays

High Electron Mobility (HEM) varactor structures have been studied for millimeter-wave monolithic diode-grid frequency tripler array applications. The improved HEM varactor diode structures provide a highly nonlinear C-V characteristic (i.e., a steep slope of the C-V curve and a large capacitance ratio) which produces high harmonic generation efficiency and reduce the power requirement for efficiently pumping each device. The effects of the light illumination on the C-V characteristics of the Barrier-Intrinsic-N⁺ (BIN) varactor diode have also been studied and the results will be discussed in this paper. In the development of a monolithic diode-grid frequency multiplier array, the low-loss quasioptical configuration is used for the construction of the multiplier circuit. The study of the effects of the light illumination on the C-V characteristics of varactor diode is important in understanding the potential applications of the quasi-optical varactor diode-grid frequency multiplier array circuit.     

Improved MOS capacitor measurements using the Q-C method

We describe a method for determining band bending vs gate bias, doping profile and oxide charge density by simultaneous measurement of charge and high frequency MOS capacitance as a function of applied voltage. This charge-capacitance or Q-C method is compared with the usual MOS measurements for the same properties. We find the Q-C method is more accurate and more routine than methods presently in use.In addition, accurate and systematic procedures are introduced for (1) finding the additive constant in the band bending vs gate bias relation, (2) eliminating interface trap error in the doping profile, (3) extrapolation of the doping profile to the interface in the region inaccessible to measurement, (4) correction of oxide charge and work-function determination for interface trap errors and effects of nonuniform doping profiles.     

Tunable BST capacitor loss compensation using active circuit

The compensation of the ohmic and the material dielectric losses in a barium strontium titanate (BST) capacitor using an active circuit is reported in this letter. The negative resistance (NR) circuit creates an effective conductance of -|G/sub n/| which adds to the positive conductance of the passive BST-based tuned capacitor. As a result, the compensation of the losses is significantly improved in the hybrid circuit by more than 50%. To our knowledge, this is the first work in tunable BST capacitor loss compensation using a NR circuit ever reported.     

1.1 Gb/s pseudorandom pulse-code modulation of 1.27 ?m wavelength c.w. InGaAsP/InP d.h. lasers

Pulse-code modulation of InGaAsP/InP d.h. injection lasers at a 1.1. Gb/s rate in a room-temperature environment has been demonstrated. The operating wavelength was 1.27 ?m. Fabrication and characteristics of the lasers, design of the 1.1 Gb/s circuitry, and performance of the experimental transmitter are described briefly.     

Design and analysis of negative capacitor by using MOSFETs

In this paper, a new circuit to synthesise negative capacitor by using MOSFETs is proposed. This circuit has been analysed exactly. Output admittance, value of negative capacitor and frequency limitations of proposed architecture, has been investigated accurately and related equations are obtained theoretically in presence of all parasitic capacitors. Also, this new negative capacitor structure is simulated in TSMC 0.13 µm CMOS Technology. Simulation results confirm the analytical predictions. By variation of g_m and C_X in proposed architecture, negative capacitor can be obtained in higher frequencies up to 15 GHz.     

New inductance and capacitor floatation schemes using current conveyors

The letter reports two circuits simulating ideal floating inductances and a capacitor floatation scheme using grounded copacitors. Both the inductances and capacitors are tunable through a single resistance and it has been shown that it is possible to simulate these realisations with unmatched passive components.     

Adaptive hierarchical modulation for simultaneous voice and multiclass data transmission over fading channels

In this paper, a new technique for simultaneous voice and multiclass data transmission over fading channels using adaptive hierarchical modulation is proposed. According to the link quality, the proposed scheme changes the constellation size as well as the priority parameters of the hierarchical signal constellations and assigns available subchannels (i.e., different bit positions) to different kinds of bits. Specifically, for very bad channel conditions, it only transmits voice with binary phase-shift keying (BPSK). As the channel condition improves, a variable-rate adaptive hierarchical M-ary quadrature amplitude modulation (M-QAM) is used to increase the data throughput. The voice bits are always transmitted in the lowest priority subchannel (i.e., the least significant bit (LSB) position) of the quadrature (Q) channel of the hierarchical M-QAM. The remaining (log/sub 2/M-1) subchannels, called data subchannels, are assigned to two different classes of data according to the selected priority parameters. Closed-form expressions as well as numerical results for outage probability, achievable spectral efficiency, and average bit error rate (BER) for voice and data transmission over Nakagami-m fading channels are presented. The adaptive techniques employing hybrid binary shift keying (BPSK)/M-ary AM (M-AM) and uniform M-QAM for simultaneous voice and two different classes of data transmission are also extended. Compared to the extended schemes, the new proposed scheme is spectrally more efficient for data transmission, while keeping the same outage probability for voice and data (both classes) as the scheme employing BPSK/M-AM. The new scheme also provides, as a by-product, a spectrally efficient way of transmitting voice and a single-class data.     

Telephony-based voice pathology assessment using automated speech analysis

A system for remotely detecting vocal fold pathologies using telephone-quality speech is presented. The system uses a linear classifier, processing measurements of pitch perturbation, amplitude perturbation and harmonic-to-noise ratio derived from digitized speech recordings. Voice recordings from the Disordered Voice Database Model 4337 system were used to develop and validate the system. Results show that while a sustained phonation, recorded in a controlled environment, can be classified as normal or pathologic with accuracy of 89.1%, telephone-quality speech can be classified as normal or pathologic with an accuracy of 74.2%, using the same scheme. Amplitude perturbation features prove most robust for telephone-quality speech. The pathologic recordings were then subcategorized into four groups, comprising normal, neuromuscular pathologic, physical pathologic and mixed (neuromuscular with physical) pathologic. A separate classifier was developed for classifying the normal group from each pathologic subcategory. Results show that neuromuscular disorders could be detected remotely with an accuracy of 87%, physical abnormalities with an accuracy of 78% and mixed pathology voice with an accuracy of 61%. This study highlights the real possibility for remote detection and diagnosis of voice pathology.     

CW operation of monolithic arrays of surface-emitting AlGaAs diodelasers with dry-etched vertical facets and parabolic deflecting mirrors

A monolithic two-dimensional array of surface-emitting AlGaAs diode lasers with dry-etched vertical facets and parabolic deflecting mirrors was mounted junction-side up on a W/Cu microchannel heatsink and evaluated under continuous-wave (CW) operating conditions. Both the facets and parabolic deflecting mirrors were etched using chlorine ion-beam-assisted etching. Threshold current densities of different sections of the array were consistently around 240 A/cm², and measured CW differential quantum efficiencies were in the 46-48% range. CW power densities as high as 148 W/cm² were achieved with an average temperature rise of less than 25°C in this junction-side-up configuration