Gallium nitride high electron mobility transistors (GaN HEMTs) were developed for millimeter-wave high power amplifier applications. The device with a gate length of 80 nm and an InAlN barrier layer exhibited high drain current of more than 1.2 A/mm and high breakdown voltage of 73,V. A cut-off frequency $ extrm{f}_{ extrm{T}}$ of 113,GHz and maximum oscillation frequency $ extrm{f}_{ extrm{max}}$ of 230,GHz were achieved. The output power density reached 1 W/mm with a linear gain of 6.4,dB at load-pull measurements at 90,GHz. And we extracted equivalent circuit model parameters of the millimeter-wave InAlN/GaN HEMT and showed that the model was useful in simulating the millimeter-wave power performance. Also, we report a preliminary constant bias stress test result.

In the early phases of the system development process, stakeholders exchange ideas and describe requirements in natural language. Requirements described in natural language tend to be vague and include logical inconsistencies, whereas logical consistency is the key to raising the quality and lowering the cost of system development. Hence, it is important to find logical inconsistencies in the whole requirements at this early stage. In verification and validation of the requirements, there are techniques to derive logical formulas from natural language requirements and evaluate their inconsistencies automatically. Users manually chunk the requirements by paragraphs. However, paragraphs do not always represent logical chunks. There can be only one logical chunk over some paragraphs on the other hand some logical chunks in one paragraph. In this paper, we present a practical approach to detecting logical inconsistencies by clustering technique in natural language requirements. Software requirements specifications (SRSs) are the target document type. We use k-means clustering to cluster chunks of requirements and develop semantic role labeling rules to derive “conditions” and “actions” as semantic roles from the requirements by using natural language processing. We also construct an abstraction grammar to transform the conditions and actions into logical formulas. By evaluating the logical formulas with input data patterns, we can find logical inconsistencies. We implemented our approach and conducted experiments on three case studies of requirements written in natural English. The results indicate that our approach can find logical inconsistencies.

In this paper, we describe the operation of circuits capable of more than 40-Gbit/s that we have developed using InP HEMT technology. For example, we succeeded in obtaining 43-Gbit/s operation for a full-rate 4:1Multiplier (MUX), 50-Gbit/s operation for a Demultiplexer (DEMUX), 50-Gbit/s operation for a D-type flip-flop (D-FF), and a preamplifier with a bandwidth of 40 GHz. In addition, the achievement of 90-Gbit/s operation for a 2:1MUX and a distributed amplifier with over 110-GHz bandwidth indicates that InP HEMT technology is promising for system operations of over 100 Gbit/s. To achieve these results, we also developed several design techniques to improve frequency response above 80 GHz including a symmetric and separated layout of differential elements in the basic SCFL gate and inverted microstrip.

We developed a new millimeter-wave plastic chip size package (CSP) to operate up to 100 GHz by using a thin-film substrate. It has a flip-chip distributed amplifier with inverted microstrip lines and the amplifier has a bandwidth of beyond 110 GHz. The transmission line on the substrate consists of grounded coplanar waveguides that yield low insertion loss and high isolation characteristics in coupled lines even in mold resin in comparison with conventional microstrip lines. The CSP amplifier achieved a gain of 7.8 dB, a 3-dB bandwidth of 97 GHz, and operated up to 100 GHz. To the best of our knowledge, this value is the highest operating frequency reported to date for a distributed amplifier sealed in a plastic CSP. We also investigated the transmission characteristics of lead-free solder bumps through experiments by assemblying CSPs on printed circuit boards and modeling them so that we could design the packages accurately.