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A 40 GHz Linear Driver Amplifier for Optical ATE using GaN HEMT with InGaN Back Barrier

Author	Advantest Laboratories Ltd.　Takahiro Tsushima others
Summary	With continuously increasing data traffic, automated test equipment (ATE) will be demanded in optical communication markets. In this paper, we describe a linear driver amplifier for optical ATE using newly developed Gallium Nitride high electron mobility transistor (GaN HEMT) that can be expected to have large output voltage swing and high linearity in high frequency band. The linear driver amplifier employing distributed amplifier configuration shows a small-signal gain of 12 dB, -3 dB bandwidth of 44 GHz and an output eye amplitude of 8.4 Vpp. In addition, a clear output eye diagram is observed at 40 Gbaud non-return-to-zero (NRZ) waveform.
Key Words	ATE, MMIC, GaN HEMT, Distributed, Amplifier

Ultra-Wideband Modulation Signal Measurement Using Local Sweep Digitizing Method

Author	Advantest Laboratories Ltd.　Koji Asami others
Summary	Recently, bandwidth for wireless communications are getting wider, i.e. 400 MHz for the 5th generation mobile communication (5G), and about 2 GHz for wireless LAN (IEEE 802.11ad). To evaluate the transceiver devices used in these communications, a high-speed waveform digitizer is required. In this paper, the "Local Sweep Digitizing Method" which accurately captures ultra-wideband signals covering 2 GHz with low cost is introduced. It is a method of decomposing a wideband signal transmitted at a high frequency into subband signals of several hundred megahertz bandwidths while downconverting it to an intermediate frequency, and capturing it for each subband signal by a low speed waveform digitizer. The captured waveform is synthesized by post digital processing. At this time, a correction process for matching the carrier phase and the conversion gain of each subband signal is performed. In this method, an ultra-wideband signal can be captured by a single low-speed high-resolution analog-to-digital converter (ADC) and the measurable bandwidth can be easily controlled by adjusting the Local Sweep section.
Key Words	5G, Wireless LAN, Transceiver, ATE, waveform digitizer, subband synthesis

Estimation of fogging effect in E-Beam direct writer for photonic crystal pattern

Author	Nanotechnology Business Group, System Engineering Department, SE Section 1　Hirofumi Hayakawa others
Summary	E-Beam direct drawing machines are mainly used for research purposes such as LSI circuit verification and prototype production. By the remarkable progress of silicon photonics devices and gate parts for 5G, the opportunity to write large area by E-Beam direct writing has been increased [1,2]. In writing large area, fogging effect is one of major factor to make CD controllability worse and correction methods have been reported [3]. In this research, by E-Beam writer, F7000S(Advantest), we conducted the test to determine the range and the degree of fogging effect. Based on this, actual photonic crystal pattern was exposed using two kinds of resists. The contents will be reported.
Key Words	E-Beam writer, CD, fogging effect