Abstract—In this paper, we propose an algorithm for suppressing intercarrier interference due to phase noise in coded orthogonal frequency division multiplexing (OFDM) systems. The algorithm approximates the phase-noise waveform by using a Fourier series approximation for the current phase-noise realization. Thereby, it cancels the effects of the phase noise beyond the standard common phase error correction used in contemporary OFDM standards. The algorithm requires that the correlation properties of the intercarrier interference are known. We calculate these properties in terms of the phase-noise spectral correlation matrix for both Wiener and Ornstein–Uhlenbeck phase-noise models, respectively. This modeling corresponds to a free-running oscillator, as well as a phase-locked loop realization of the local oscillator in orthogonal frequency division multiplexing transceivers. For both transceiver configurations, we investigate the performance of the proposed algorithm. It is demonstrated that the new algorithm achieves as much as one order of magnitude better performance in terms of packet/bit error rate when compared to a receiver with only the common phase error suppression. Index Terms—Orthogonal frequency division multiplexing (OFDM), phase-locked loop, phase noise. I.

Abstract—We present observations of quantum confinement and quantum-confined Stark effect (QCSE) electroabsorption in Ge quantum wells with SiGe barriers grown on Si substrates, in good agreement with theoretical calculations. Though Ge is an indirect gap semiconductor, the resulting effects are at least as clear and strong as seen in typical III–V quantum well structures at similar wavelengths. We also demonstrate that the effect can be seen over the C-band around 1.55-µm wavelength in structures heated to 90 ◦C, similar to the operating temperature of silicon electronic chips. The physics of the effects are discussed, including the effects of strain, electron and hole confinement, and exciton binding, and the reasons why the effects should be observable at all in such an indirect gap material. This effect is very promising for practical high-speed, low-power optical modulators fabricated compatible with mainstream silicon electronic integrated circuits. Index Terms—Electroabsorption effect, germanium, optical interconnections, optical modulators, quantum-confined Stark effect (QCSE), silicon. I.

Radio-frequency power amplifiers (RF PAs) are among the key building blocks for wireless communication systems. They are used to amplify the RF signal at the output of the transmitter before the RF signal is fed into the antenna. This study evaluates the Si MOSFET, the Si LDMOS FET, the SiGe HBT, and the AlGaAs/InGaAs pHEMT as switches for use in a current-mode class-D (CMCD) RF switching-mode PA. The goal of this study was to determine which of the above devices delivers the highest efficiency at 0.8-1.0 GHz and 1.8-2.2 GHz for 10-20 W of output power, and at 5.8 GHz for 3 W of output power. The study presents a detailed analysis of a CMCD PA based upon spectrum-limited waveforms for the device voltage and current. An analytical expression for the power added efficiency (PAE) of a CMCD PA employing FET devices is derived as a function of the mobility µn, oxide cap. Cox, overlap cap. Cov, gate sheet res. Rg,sheet, gate contact res. Rg,contact, source res. Rs, number of fingers F, gate width W, gate length L, the supply voltage Vdd, the shunt-tank res. R, and the input voltage amplitude ˆ Vin. A sensitivity analysis revealed that Cox,

Abstract—We present the RF characterization of silicon–germanium heterojunction bipolar transistor (SiGe HBT) power amplifiers (PA) under load mismatched conditions. Experimental results demonstrate a strong dependence of a PA’s RF performance on the phase of mismatched antenna loads. For a load mismatch of voltage standing-wave ratio (VSWR) of 10: 1, the 1-dB compressed RF output power ( 1dB), transducer gain (), output third-order intercept point, and power-added efficiency differ by 7.5 dBm, 8.1 dB, 8.3 dBm, and 15%, respectively, between the optimal and worst phase conditions, for an SiGe HBT PA biased at CC =33 V, collector current CE =400mA, and frequency of 1.88 GHz. At the optimal phase condition up to VSWR of 10: 1, the SiGe HBT PA maintains its linearity, RF output power, gain, and efficiency close to that at a VSWR of 1: 1. At all the nonoptimal phases, the deterioration in the RF performance increases with the magnitude of load mismatches. The nonlinear characteristic of a PA under load mismatches is due to amplitude and phase-distortion mechanisms. Index Terms—Antenna, distortion, linearity, load, mismatch, phase, power amplifier (PA), SiGe HBT, voltage standing-wave

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This paper reports a numerical modeling of a NPN SiGe heterojunction bipolar transistor (HBT) taking into account the impact of electrically active defects in the HBT device. The purpose was to investigate the DC and low frequency noise performances of SiGe HBT taking into account effect of base implantation defects. These defects physically located at emitter-base junction, are responsible for parasitic current fluctuations at the origin of low frequency noise in devices. The first part of the paper deals with degradation of DC characteristics of the device due to the influence of extrinsic base implantation defects. The aim was to identify the parasitic effects of implantation defects on the HBT static characteristics. Generally, the presence of these defects in the structure, results in a no ideal behavior of the base currents. The second part of the paper deals with the analysis of low frequency noise (LFN) in the SiGe HBT. Usually, LFN of these devices was related to the existence of defects and imperfections in the semiconductor. The purpose was to examine the impact of implantation defects on the noise in SiGe HBTs. In this fact, the LFN of SiGe HBT was characterized, and a discussion of the possible physical origins of low-frequency noise is presented.