Technique for suppression of pattern dependence in a semiconductor-optical-amplifier wavelength converter

Wavelength converters that employ cross-gain modulation (XGM) in semiconductor optical amplifiers (SOAs) are limited in bit rate by the amplifier's pattern dependent response. We substantially suppress this pattern dependence by converting the phase modulation at the data transitions to amplitude modulation using a fiber grating filter. We use this technique to obtain error-free wavelength conversion of 10-Gb/s nonreturn-to-zero (NRZ) data using an SOA that showed an error floor at 10/sup -5/ bit-error rate (BER) when used alone.     

ESD issues in compound semiconductor high-frequency devices and circuits

The need of ESD protection for high frequency devices and circuits is underlined by reviewing the compound semiconductor material properties with emphasis on ESD stress and by collecting their ESD failure thresholds. Basic requirements for possible ESD protection structures in the microwave frequency regime are discussed and possible ESD protection devices and circuit concepts are proposed.     

A Surface Tailoring Method of Ultrathin Polymer Gate Dielectrics for Organic Transistors: Improved Device Performance and the Thermal Stability Thereof

Tailoring the surface of the dielectric layer is of critical importance to form a good interface with the following channel layer for organic thin film transistors (OTFTs). Here, a simple surface treatment method is applied onto an ultrathin (<15 nm) organosilicon‐based dielectric layer via the initiated chemical vapor deposition (iCVD) to make it compatible with organic semiconductors without degrading its insulating property. A molecular‐thin oxide capping layer is formed on a 15 nm thick poly(1,3,5‐trimetyl‐1,3,5‐trivinyl cyclotrisiloxane) (pV3D3) by a brief oxygen plasma treatment. The capping layer greatly enhances the thermal stability of the dielectrics, without degrading the original mechanical flexibility and insulating performance of the dielectrics. Moreover, the surface silanol functionalities formed by the plasma treatment can also be utilized for the surface modification with silane compounds. The surface‐modified dielectrics are applied to fabricate low‐voltage operating (<5 V) pentacene‐based OTFTs. The highest field‐effect mobility of the device with the surface‐treated 15 nm thick pV3D3 is 0.59 cm² V^?1 s^?1, which is improved up to two times compared to the TFT with the pristine pV3D3. It is believed that the simple surface treatment method can widely extend the applicability of the highly robust, ultrathin, and flexible pV3D3 gate dielectrics to design the surface of the dielectrics to match well various kinds of organic semiconductors.     

100-Gb/s 2/sup 7/-1 and 54-Gb/s 2/sup 11/-1 PRBS generators in SiGe bipolar technology

This paper presents two monolithic pseudorandom bit sequence (PRBS) generators. One circuit uses a seven-stage shift register operating with a half-rate clock and provides output signals up to 100 Gb/s. The second circuit contains an eleven-stage shift register operating with a full-rate clock up to 54 Gb/s. Both PRBS generators provide a wide range of data rates down to below 1 Gb/s simply by changing the frequency of the external clock signal without the need of any further adjustments. The integrated circuits provide a trigger output which can be switched between eye and pattern display. Furthermore, they contain additional circuitry to guarantee automatic start after power-on. The circuits are manufactured in a 200-GHz f/sub T/ SiGe bipolar technology. They each have a chip size of 900/spl times/700 /spl mu/m/sup 2/ and consume 1.5 and 1.9 W, respectively.     

Effect of different chemical treatments of surface on the height of Al-<Emphasis Type=Italic>p</Emphasis>-SiGe and Au-<Emphasis Type=Italic>n</Emphasis>-SiGe barriers

The effect of different chemical treatments on the properties of Au-n-SiGe and Al-p-SiGe Schottky barriers has been investigated. Etching under different conditions was used to prepare surfaces with different densities of surface states (D _ss). It is shown that the barrier height in the structures under study correlates with the D _ss value and germanium content in the Si_{1 − x} Ge _x alloy.     

Long-wavelength 256×256 GaAs/AlGaAs quantum well infraredphotodetector (QWIP) palm-size camera

A 9 μm cutoff 256×256 palm-size quantum well infrared photodetector (QWIP) camera weighing only 2.5 lbs, and using 5.5 W of power has been demonstrated. Excellent imagery, with a noise equivalent differential temperature (NEΔT) of 23 mK has been achieved. It is well known that QWIP has very low 1/f noise, high operability, and uniformity. As a result, this camera uses a prerecorded nonuniformity correction table (i.e., gains and offsets) stored in its read-only-memory during operation, which enabled the miniaturization of this camera. In this paper, we discuss the development of this very sensitive long-wavelength infrared (LWIR) camera based on a GaAs/AlGaAs QWIP focal plane array (FPA) and its performance in terms of quantum efficiency, NEΔT, MRDT, uniformity, and operability     

Fully integrated SiGe VCOs with powerful output buffer for 77-GHz automotive Radar systems and applications around 100 GHz

It is demonstrated that SiGe bipolar technologies are well suited for voltage-controlled oscillators (VCOs) in 77-GHz automotive radar systems. For this, the design of a VCO with powerful output buffer (with good decoupling capability and high output power), comparatively wide tuning range, and reasonably low phase noise is described. To achieve the required high output power, the potential operating range of the output transistors, limited by high-current effects and avalanche breakdown, respectively, had to be exploited using adequate transistor models. The VCOs need a single supply voltage only and have been fully integrated (including resonant circuit and output buffer) on a single small (1 mm/sup 2/) chip, demonstrating their low-cost potential. Experimental results showed, at a center frequency of around 77 GHz, a usable tuning range of 6.7 GHz and a phase noise of -97 dBc/Hz at 1-MHz offset frequency averaged over this range. In addition, the center oscillation frequency can be coarsely adjusted within a wide range by cutting links in the upper metallization layer. The total signal power delivered by both buffer outputs together is as high as 18.5 dBm at a power consumption of 1.2 W. Simulations let us expect a potential doubling of the output power (for two or four outputs) by extension of the output buffer. To get an impression of the maximum frequency achievable with the circuit concept and technology used, a second VCO (again with buffered output) has been developed. To the best of the authors' knowledge, the measured maximum oscillation frequency of about 100 GHz, at 12.4-dBm total output power (14.3 dBm at 99 GHz), is a record value for SiGe VCOs with buffered output operating at their fundamental frequency. The usable tuning range is still 6.2 GHz.     

On the use of Reed-Solomon codes in improving digital FMtransmission performance in Rayleigh fading

Reed Solomon codes with interleaving are used in a binary FM transmission affected by Rayleigh fading as encountered in land mobile radio. A new decoding algorithm is proposed which can be implemented in simple hardware. The error performance of the binary FM system with the RS code with one and two degrees of interleaving is measured. A significant reduction of error rate floor as a function of fading speed is noted and discussed