In the cochlear nucleus, there is a magnocellular core of neurons whose axons form the ascending auditory pathways. Surrounding this core is a thin shell of microneurons called the granule cell domain (GCD). The GCD receives auditory and nonauditory inputs and projects in turn to the dorsal cochlear nucleus, thus appearing to serve as a central locus for integrating polysensory information and descending feedback. Nevertheless, the source of many of these inputs and the nature of the synaptic connections are relatively unknown. We used the retrograde tracer Fast Blue to demonstrate that a major projection arises from the contralateral pontine nuclei (PN) to the GCD. The projecting cells are more densely located in the ventral and rostral parts of the PN. They also are clustered into a lateral and a medial group. Injections of anterograde tracers into the PN labeled mossy fibers in the contralateral GCD. The terminals are confined to those parts of the GCD immediately surrounding the ventral cochlear nucleus. There is no PN projection to the dorsal cochlear nucleus. These endings have the form of bouton and mossy fiber endings as revealed by light and electron microscopy. The PN represent a key station between the cerebral and cerebellar cortices, so the pontocochlear nucleus projection emerges as a significant source of highly processed information that is introduced into the early stages of the auditory pathway. The cerebropontocerebellar pathway may impart coordination and timing cues to the motor system. In an analogous way, perhaps the cerebropontocochlear nucleus projection endows the auditory system with a timing mechanism for extracting temporal information.

It is well known that, in the millimeter (mm-wave) and sub-mm-wave range, on-wafer S-parameter measurements are often inaccurate and suffer from serious systematic artifacts. In this paper, we confirm that these artifacts are related to spurious wave modes that are excited and propagate in the substrate. These parasitic wave components may be scattered at neighboring structures on the wafer and cause detrimental crosstalk. While these parasitic components deteriorate the measurement itself, an even more serious complication arises from the fact that these modes are already present in the calibration measurement and are unintentionally imported and superposed to the measurement data. In this paper, we present a new type of RF pad with novel screening features and show that these parasitic modes can be efficiently suppressed by the use of proper on-wafer couple structures. Moreover, a novel calibration substrate and method is presented and demonstrated to be capable to remove spurious artifacts from S-parameter measurements up to 450 GHz.

In the cochlear nucleus, there is a magnocellular core of neurons whose axons form the ascending auditory pathways. Surrounding this core is a thin shell of microneurons called the granule cell domain (GCD). The GCD receives auditory and nonauditory inputs and projects in turn to the dorsal cochlear nucleus, thus appearing to serve as a central locus for integrating polysensory information and descending feedback. Nevertheless, the source of many of these inputs and the nature of the synaptic connections are relatively unknown. We used the retrograde tracer Fast Blue to demonstrate that a major projection arises from the contralateral pontine nuclei (PN) to the GCD. The projecting cells are more densely located in the ventral and rostral parts of the PN. They also are clustered into a lateral and a medial group. Injections of anterograde tracers into the PN labeled mossy fibers in the contralateral GCD. The terminals are confined to those parts of the GCD immediately surrounding the ventral cochlear nucleus. There is no PN projection to the dorsal cochlear nucleus. These endings have the form of bouton and mossy fiber endings as revealed by light and electron microscopy. The PN represent a key station between the cerebral and cerebellar cortices, so the pontocochlear nucleus projection emerges as a significant source of highly processed information that is introduced into the early stages of the auditory pathway. The cerebropontocerebellar pathway may impart coordination and timing cues to the motor system. In an analogous way, perhaps the cerebropontocochlear nucleus projection endows the auditory system with a timing mechanism for extracting temporal information.

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A metamorphic high electron mobility transistor (mHEMT) technology with 20 nm gate length for manufacturing of terahertz monolithic integrated circuits (TMICs) is presented. The passive elements include up to four interconnection metallization layers separated by low-k dielectrics (BCB), SiN and air which can be used to realize front side signal lines. Shielding the substrate from the electromagnetic field on the wafer front side eliminates the need of a costly back side process including wafer thinning, through substrate via etching and back side metallization. The semiconductor heterostructure of the mHEMT comprises a strained pure InAs channel with high electron mobility and high electron density for proper device scaling. The realized mHEMTs achieve a source resistance r S of 0.12 Ωmm which is required to minimize resistive losses in combination with an extrinsic maximum transconductance g m_max of 2850 mS/mm. Elaborated on wafer calibration procedures and optimized test transistor layouts were used to improve the precision of the S-parameter measurements up to a frequency of 450 GHz which than could be used for model extraction. The presented 20 nm mHEMT technology was employed for the design of a compact eight stage low-noise amplifier (LNA) using miniaturized microstrip lines on BCB. The measured small signal gain of the LNA exceeds 15 dB from 500 -635 GHz.Keywords-low-noise amplifier (LNA), metamorphic high electron mobility transistor (mHEMT), terahertz monolithic integrated circuit (TMIC).I.

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