Digital European Cordless Telephone Research Articles

A New Configuration of Surface Acoustic Wave Intermediate-Frequency Filter with Compact Size and Improved Insertion Loss

Size reduction is always a major challenge to surface acoustic wave (SAW) manufacturers. For some years, commercial SAW filter designers have been developing various configurations of SAW filters just to fit into a smaller package. In this work, a new single-phase unidirectional transducer (SPUDT) based intermediate-frequency (IF) filter with improved insertion loss and compact size is proposed. This filter has an architecture that combines electrode-width controlled single-phase unidirectional transducer (EWC-SPUDT) and comb-type SPUDT. As a result of this improvement, a filter for IF-filtering of Digital European Cordless Telephone (DECT) system can be squeezed into a surface-mount device (SMD) 7.0×5.0 mm2 package. The performance of this filter even excels most commercial available IF filters in the same application.

The silicon radio decade

During the 1990s, we witnessed a string of advances in silicon RF integration: from the introduction of the first integrated silicon bipolar radios for groupe special mobile (GSM) and digital European cordless telephone in the late 1980s toward full single-chip integration capabilities based on silicon-germanium BiCMOS technologies. Where RF design used to be a black art, it is becoming a "normal practice" today. In this paper, the authors look back on the past ten years of circuits, silicon technology, and system research with roots in standardization and a scope reaching from the early ideas to the final product success on the market and some perspective toward new concepts and systems.

Pre-Compensation for Rayleigh Fading Channels in Time Division Duplex OFDM Systems

Coherent demodulation results in good detection performance but requires channel estimation. Fading pre-compensation (precoding) at the transmitter can lead to low-complex receiver structures with good performance capabilities, without the need for channel estimation. Time division duplex systems based on orthogonal frequency division multiplex (OFDM) are particularly suited to this because intersymbol interference effects can be neglected, simplifying transmitter adjustments. Methods that involve amplitude and/or phase pre-compensation are compared in terms of resulting bit error rate and increase in peak-to-average power ratio. Dynamic channels degrade the performance as the block lengths get longer. For a certain block length the performance degrades below that of traditional differential decoding. A block length of up to 40 times that used in the Digital European Cordless Telephone system, DECT, is possible using channel estimation and ideal Wiener prediction.

Chip-package codesign of a low-power 5-GHz RF front end

Future high-performance wireless communication applications such as wireless local area networks (WLANs) around 5 GHz require low-power and highly integrated transceiver solutions. The integration of the RF front end especially poses a great challenge in these applications, as traditional front-end implementations require a large number of external passive components. In this paper, we present the single-package integration of complete transceivers based on a thin-film multichip module (MCM) technology with integrated passives. The MCM substrate is a a common carrier onto which different ICs are mounted. passive components such as RF bandpass filters, inductors, capacitors, and resistors are directly integrated into the MCM substrate with the use of the multilayer structure of the MCM technology. The "system-on-a-package" approach is illustrated with a voltage-controlled oscillator for Digital European Cordless Telephone (DECT) applications and a 5-GHz WLAN front end. These examples indicate that this approach yields a compact low-power implementation of complete transceivers for high-performance wireless applications.

A single-chip Si-bipolar 1.6-GHz VCO with integrated-bias network

A single-chip 2.7-V voltage-controlled oscillator (VCO) with an integrated-bias network has been implemented in an Si-bipolar process with an f/sub T/ of 25 GHz. With an on-chip resonator consisting of vertically coupled inductors and varactor diodes, an oscillation frequency of 1.56 GHz was measured. A careful design of the oscillator and bias network was necessary to achieve a phase noise performance of -139 dBc/Hz at 4.7 h MHz off carrier. The tuning sensitivity was 100 MHz/V, which is sufficient to compensate for production tolerances. The VCO can be used as a building block for single-chip transceivers in digital European cordless telephone or global system for mobile communication systems.