Search

This article describes the successful development and the performance of X-band 100 W pulsed SSPA using a 25 W GaN-on-SiC high electron mobility transistor (HEMT). The GaN HEMT with a gate length of 0.25 µm and a total gate width of 8 mm were fabricated. The GaN HEMT provide a linear gain of 8 dB with 25 W output power operated at 30 V drain voltage in continuous wave (CW)-operation with a power added efficiency of 43% at X-band. It also shows a maximum output power density of 3 W/mm. The X-band pulsed SSPA exhibited an output power of 100 W (50 dBm) with a power gain of 53 dB in a frequency range of 9.2–9.5 GHz. This 25 W GaN HEMT and X-band 100 W pulsed SSPA are suitable for the radar systems and related applications in X-band. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:212–216, 2015

In this article, 60 GHz MMIC down-conversion mixers for a 60 GHz communication system are designed and fabricated on-chip using a 0.12 μm GaAs PHEMT process technology with an fT of 78 GHz and fmax of 190 GHz.The characteristics of a 60 GHz monolithic cascode mixer with an open stub microstrip line are compared with those of a 60 GHz monolithic cascode mixer without an open stub microstrip line, which are integrated on-chip including matching and bias circuits. The 60 GHz monolithic cascode mixer with an open stub microstrip line measured at RF 60 GHz show a conversion gain of −16 dB, LO to RF isolation of 21.5 dB, and LO to IF isolation of 40.5 dB. Especially in the case of the mixer, the LO to IF isolation characteristic is much better than that of the 60 GHz monolithic cascode mixer without an open stub microstrip line. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1341–1345, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25191

We present an analysis of microstrip coupled lines (MCLs) used to improve the stability of a 60 GHz narrowband amplifier. The circuit has a 4-stage structure implementing MCLs instead of metal-insulator-metal (MIM) capacitors for the unconditional stability of the amplifier and yield enhancement. The stability parameter, U, is used to compare the stability of MCLs with that of MIM capacitors. Experimental results show that MCLs are more stable than MIM capacitors with the same capacitances as MCLs because the parasitic parallel resistances of MCLs are lower than those of MIM capacitors. Moreover, the bandwidth of an amplifier using MCLs is narrower than one using MIM capacitors because the parasitic series inductances of MCLs are higher than those of MIM capacitors.

This study examines the effect of multiknowledge individuals (especially those possessing both marketing and technological knowledge) on performance in cross-functional new product development teams. A survey of 62 cross-functional teams shows that the proportion of multiknowledge individuals has an indirect positive effect through information sharing on product innovativeness and a direct positive effect on time efficiency of new product development teams.

Proneural basic helix–loop–helix proteins are key regulators of neurogenesis but their ‘proneural’ function is not well understood, partly because primary targets have not been systematically defined. Here, we identified direct transcriptional targets of the bHLH proteins Neurogenin and NeuroD and found that primary roles of these transcription factors are to induce regulators of transcription, signal transduction, and cytoskeletal rearrangement for neuronal differentiation and migration. We determined targets induced in both Xenopus and mouse, which represent evolutionarily conserved core mediators of Neurogenin and NeuroD activities. We defined consensus sequences for Neurogenin and NeuroD binding and identified responsive enhancers in seven shared target genes. These enhancers commonly contained clustered, conserved consensus‐binding sites and drove neural‐restricted transgene expression in Xenopus embryos. We then used this enhancer signature in a genome‐wide computational approach to predict additional Neurogenin/NeuroD target genes involved in neurogenesis. Taken together, these data demonstrate that Neurogenin and NeuroD preferentially recognize neurogenesis‐related targets through an enhancer signature of clustered consensus‐binding sites and regulate neurogenesis by activating a core set of transcription factors, which build a robust network controlling neurogenesis.

We report on the fabrication of an AlGaAs/InGaAs/GaAs pseudomorphic high electron mobility transistor (PHEMT) using a dielectric-defined process. This process was utilized to fabricate 0.12 µm × 100 µm T-gate PHEMTs. A two-step etch process was performed to define the gate footprint in the SiNx. The SiNx was etched either by dry etching alone or using a combination of wet and dry etching. The gate recessing was done in three steps: a wet etching for removal of the damaged surface layer, a dry etching for the narrow recess, and wet etching. A structure for the top of the T-gate consisting of a wide head part and a narrow lower layer part has been employed, taking advantage of the large crosssectional area of the gate and its mechanically stable structure. From s-parameter data of up to 50 GHz, an extrapolated cut-off frequency of as high as 104 GHz was obtained. When comparing sample C (combination of wet and dry etching for the SiN x ) with sample A (dry etching for the SiNx), we observed an 62.5% increase of the cut-off frequency. This is believed to be due to considerable decreases of the gate-source and gate-drain capacitances. This improvement in RF performance can be understood in terms of the decrease in parasitic capacitances, which is due to the use of the dielectric and the gate recess etching method.

ABSTTACT-We propose an inductive compensation method for a surface-mountable 10 Gbps photoreceiver module. Since many typical 10 Gbps photoreceiver modules consist of a photodetector and low-noise pre-amplifier, the impedance mismatch between the photodetector and preamplifier, as well as package parasitics, may reduce the frequency bandwidth. In this paper, we inserted an inductive component between the photodetector and pre-amplifier in order to create frequency bandwidth expansion. From the measurement results, we have found that the proposed technique can increase the -3 dB bandwidth about 4.2 GHz wider compared with an uncompensated module. And, from a bit-error rate (BER) test, we observed -15.7 dB sensitivity at 10 - 1 2 BER This inductive compensation can be implemented easily and is compatible with common manufacturing processes of photoreceiver modules.

We have grown an AlIn(Ga)N/GaN heterostructure which is a promising alternative to the AlGaN/GaN heterostructure. The mobility and the carrier concentration of the two-dimensional electron gas (2DEG) formed at the AlIn(Ga)N/GaN heterointerface were strongly dependent on both the growth temperature and pressure. Two optimized growth conditions for the heterostructure with a low sheet resistance less than 300 Ω/sq were obtained by varying the growth temperature and pressure from 750 to 1070 °C and 100 to 300 torr, respectively: (i) AlIn(Ga)N/GaN heterostructure with high 2DEG carrier concentration of 2.4 × 1013 cm−2 with mobility of 1010 cm2 V−1s−1 (grown at 900 °C and 100 torr); (ii) AlIn(Ga)N/GaN heterostructure with high 2DEG mobility of 1910 cm2 V−1s−1 with carrier concentration of 1.13 × 1013 cm−2 (grown at 900 °C and 300 torr). Both structures would be useful for different purpose of device application.