Hiroshi Yamazaki

13.4-Tb/s (134 × 111-Gb/s/ch) no-guard-interval coherent OFDM transmission over 3,600 km of SMF with 19-ps average PMD

We demonstrate the record capacity-distance product of 48.2 Petabit/s.km by using 111-Gb/s no-guard-interval coherent OFDM with 2-b/s/Hz spectral efficiency.

Synthesis and Characterization of BiFeO3–PbTiO3 Thin Films through Metalorganic Precursor Solution

Perovskite (1-x)BiFeO3–xPbTiO3 thin films have been synthesized by the chemical solution deposition of metalorganic compounds. Homogeneous and stable BiFeO3–PbTiO3 precursor solutions were prepared by selecting appropriate starting materials and 2-methoxyethanol as a solvent. Perovskite BiFeO3–PbTiO3 powder samples with a composition ranging from x=0.1 to 0.5 showed weak ferromagnetism at room temperature. Perovskite BiFeO3–PbTiO3 single-phase thin films on Pt/TiOx/SiO2/Si substrates with good surface morphology were also fabricated by optimizing the PbTiO3 content. Ferroelectric polarization–electric field (P–E) hysteresis loops were observed for 0.7BiFeO3–0.3PbTiO3 thin films, although some leakage current components are included at room temperature. The electrical resistivity of the BiFeO3–PbTiO3 films was improved in the low temperature region, and the remnant polarization and coercive field of the 700 °C-prepared 0.7BiFeO3–0.3PbTiO3 thin films at -190 °C were approximately 50 µC/cm2 and 150 kV/cm, respectively. Furthermore, Mn doping into BiFeO3–PbTiO3 was effective in improving the ferroelectric properties of the resultant thin films at room temperature.

An accurate center frequency tuning scheme for 450-KHz CMOS G/sub m/-C bandpass filters

This paper describes a center frequency tuning technique for a second intermediate-frequency (IF) bandpass filter. The utilization of the step signal response ensures the direct measurement of the center frequency. This tuning technique guarantees the accuracy of the design. A 450-kHz G/sub m/-C bandpass filter tuned using this technique has been developed to integrate the IF module for personal digital cellular (PDC) handsets for use in 0.35-/spl mu/m CMOS. The filter with the tuning scheme achieves a center frequency accuracy of /spl plusmn/0.5%.

An 18mW 90 to 770MHz synthesizer with agile auto-tuning for digital TV-tuners

An 18mW 90-to-770MHz I/Q synthesizer is fabricated in a 1.2V 0.11mum CMOS process. The architecture is optimized to achieve low power and wide tuning range. A divide-by-3.5 7b VCO with an agile auto-tuning block is included. Phase noise is < -100dBc/Hz at 100kHz offset

A 1.95 GHz Fully Integrated Envelope Elimination and Restoration CMOS Power Amplifier Using Timing Alignment Technique for WCDMA and LTE

A fully integrated envelope elimination and restoration (EER) CMOS power amplifier (PA) has been developed for WCDMA and LTE handsets. EER is a supply modulation technique that first divides modulated RF signal into envelope and phase signals and then restores it at a switching PA output. Supply voltage of the switching PA is modulated by the envelope signal through a high-speed supply modulator. EER PA is highly efficient due to the switching PA and the supply modulation. However, it generally has difficulty, especially for a wide bandwidth baseband application like LTE, achieving a wide bandwidth for phase signal path and highly accurate timing between envelope and phase signals. To overcome these challenges, an envelope/phase generator based on a mixer and a limiter was proposed to generate the wide bandwidth phase signal, and a timing aligner based on a delay locked loop with a variable high-pass filter (HPF) was proposed to compensate for the timing mismatch. The chip was implemented in 90 nm CMOS technology. Measured power-added efficiency (PAE) and adjacent channel leakage ratio (ACLR) were 39% and -41 dBc for WCDMA, and measured PAE and ACLR E-UTRA1 were 32% and -33 dBc for 20 MHz-BW LTE.

Preparation of Pb(Zr, Ti)O3 thin films using all dipivaloylmethane source materials by metalorganic chemical vapor deposition

Pb-bis-dipivaloylmethane [Pb(DPM)2], Zr(DPM)4 and Ti(DPM)2(i-OC3H7)2 are developed as the new chemical vapor deposition (CVD) sources for lead zirconate titanate (PZT) thin film. The growth rate of each of the single metal oxides PbO, ZrO2 and TiO2, was studied as a function of oxygen partial pressure. The growth rates of ZrO2 and TiO2 were independent of the input oxygen partial pressure, while the growth rate of PbO increased with increasing input oxygen partial pressure. PZT films were grown on (100) MgO substrates at 2.0 Torr by metalorganic chemical vapor deposition (MOCVD). The film grown at 500°C was amorphous. The film grown at 550°C was a mixed phase of a-axis- and c-axis-oriented perovskite. The film grown at 600°C was a single-phase c-axis-oriented perovskite.

Compositional dependence of fluorescence spectra of Cr3+/Cr4+-doped calcium alumino-silicate glasses for broadband telecommunication

The compositional dependence of the optical properties of Cr-doped glasses in a calcium alumino-silicate ternary system were investigated. By 792 nm excitation, two broad emission bands centered at 1000 and 1350 nm, which were attributed to Cr3+ and Cr4+ ions, respectively, were observed. The intensity ratio of these bands changed continuously as the host composition was varied; a positive correlation between the relative intensity of the Cr4+ band and the optical basicity Λ of the host glass was observed. In glasses with Λ=0.68–0.70, the two bands became comparable in their intensities and formed an extremely broad emission band with a bandwidth of more than 500 nm as their superposition.

High-Intensity Vacuum Ultraviolet Light Source in Windowless Photochemical Vapor Deposition Reactor and Its Application to a-Si:H Deposition

Optical emission characteristics of vacuum ultraviolet light which is effective in decomposing source gases used for deposition of hydrogenated amorphous silicon were investigated. The emission line from H atoms at 121.5 nm corresponds to the absorption peak of source gases of silicon hydrides. This emission line intensity increases markedly by mixing hydrogen with helium from 5 to 10% in concentration. The deposition rate of hydrogenated amorphous silicon films by windowless photochemical vapor deposition using this strong emission line at 121.5 nm is proportional to the emission intensity, which reaches as high as 270 A/min.

3.2 A 1.95GHz fully integrated envelope elimination and restoration CMOS power amplifier with envelope/phase generator and timing aligner for WCDMA and LTE

In recent years, the demand for low cost and system-on-a-chip for mobile terminals has led to the development of a highly-integrated, low-distortion, and high-power-efficiency CMOS power amplifier (PA). To improve the power efficiency of the conventional linear PA [1-4], an envelope tracking (ET) technique, which modulates supply voltage of a linear PA, has attracted attention. However, the published power efficiency, gain and output power are not sufficient for LTE applications [5], and its typical implementation requires an external supply modulator that is a high-speed power supply circuit [6]. Envelope elimination and restoration (EER) is an alternative supply modulation technique that can further improve the power efficiency over ET by replacing the linear PA with a switching PA driven by a phase signal [7]. However, to meet the specified low distortion, especially for LTE with a wide bandwidth baseband signal, an EER PA generally has difficulty achieving a wide bandwidth for the phase signal path, and requires a high-speed supply modulator, and highly accurate timing between envelope and phase signals. To overcome these problems, this paper introduces an envelope / phase generator based on a mixer and a timing aligner based on a delay-locked loop. Additionally, they were integrated with a switching PA and a supply modulator on the same die.

A 0.3mm 2 90-to-770MHz fractional-N Synthesizer for a digital TV tuner

This paper describes a 0.3mm2 and a 90M-to-770MHz range low spurious fractional-N synthesizer, with which mobile receivers for Japanese terrestrial digital broadcasting are equipped. The synthesizer for DTV tuner needs to cover 90Mto–108MHz which is scheduled for ISDB-Tsb, and 170M-to-222MHz which is scheduled for ISDB-Tmm etc, and 470M-to-770MHz for ISDB-T. And the synthesizer needs a frequency resolution of 1/7MHz to receive each segment. In addition, it is demanded that the synthesizer minimize the macro area to reduce costs while maintaining other performance (phase noise, power consumption, tracking time, etc.) from a previous work [1].