Large-signal-based nonlinear models are developed to analyze a variety of dynamic performances in a resonant tunneling diode (RTD) with peripheral circuits such as an integrated broad band bow-tie antenna, a bias circuit and a bias stabilizer circuit. Dynamic modes of the RTD are classified by the time-domain analysis with the model. On the basis of our model, we suggest a possibility to discuss a terahertz order oscillation mode control, and the ASK modulation in several tens Gbit/sec in the RTD with the broad band antenna. Validity of the model and analysis is shown by explaining measured results of modulated oscillation signals in fabricated triple-barrier RTDs.

In this paper, we propose a nonlinear control model to characterize the AQM algorithm-GREEN. Based on this model, we analyze its performance and prove that there exists a stable oscillation when in equilibrium. Furthermore, we also investigate the effects of the factors such as bandwidth, round trip time, and load level on the amplitude and frequency of the oscillation. Theoretical analysis and simulation results indicate that GREEN algorithm is insensitive to the network conditions when the link rate and the round trip time are relatively small and becomes more sensitive to the change of network conditions when the bandwidth delay product is relatively high. For GREEN the adaptability to a wide range of network conditions is based on the compromising of the efficiency.

This paper describes an improved nonlinear GaAs FET model and its parameter extraction procedure for almost all operating conditions such as the small-signal condition, the power saturated condition, and the controlled-resistance condition. The model is capable of modeling the gate voltage dependent drain current and its derivatives in the saturated region as well as the drain voltage dependent drain current and its derivatives in the linear region. The model can take into account the frequency dispersion effects of both transconductance and output conductance. The model describes forward conduction and reverse conduction currents. Deriving the capacitance part of the model from unique charge equations satisfies charge conservation. The model accurately predicts voltage-dependent S-parameters, spurious response in an active condition and inter-modulation response in the controlled-resistance condition of a GaAs FET.

This paper proposes an improved nonlinear FET model along with its parameter extraction procedure suitable for the accurate prediction of inter-modulation product's levels (IM) and spurious responses in active and passive applications. This new model allows accurate capture of the drain current behavior and its derivatives with respect to the gate voltage and the drain voltage in the both the saturated and linear regions of the I-V biasing domain. It was found that this model accurately predicts the bias-dependent S-parameters as well as IM's levels for both amplifier and mixer applications up to mm-wave frequencies.

The design and performance of a S-band solid-state power amplifier (SSPA) module are reported. The SSPA module consisted from four MMIC power amplifiers (PA) achieves 90 W output power, 35% power added efficiency (PAE), and 80% power combine efficiency. The MMIC PA achieves over 28 W output power, 25 dB small signal gain, and over 38% PAE. This paper also describes the large-signal circuit design for the MMIC PA using an improved nonlinear FET model developed for high power amplifier applications.

Intricate Speech Communication Mode (I-SC Mode) is observed in verbal interaction during ISDN-TV conferencing. It is characterized by conflicts and multiple interactions of speech. I-SC Mode might cause mental stress to participants and be obstacles for smooth communication. However, the reasons of I-SC Mode on the environment of information transmission are hitherto unknown. Furthermore, analyses on the talks inside a conference site (LT: local talk or a talk inside a local site) and between remote sites (MT: media talk or a talk between remote sites) are originally conceived on assumed differences in cognitive distance and media intimacy. This study deals with communication effects/barriers and cognitive distance/intimacy of media correlated with audio-video transmission signals and speech modes or talk types and response delay in human speech interactions by using an innovated conference model (decision-making transaction model: DT-Model) in synchronous ISDN-TV conference systems (SYN) and asynchronous ones (ASYN). The effects of intricate communication can be predicted to a certain extent and in some ways. In I-SC Mode, because a timely answer can not be received from recipients (or partner), response time delay and response rate are analyzed. These factors are thus analyzed with an innovated dynamic model, where the recognizable acceptance of delay is evaluated. The nonlinear model shows that the larger the response time delay, the lower the response rate becomes. Comparing the response rate between SYN and ASYN, the latter is notably lower than the former. This indicates that the communication efficiency is lower in ASYN. An I-SC Mode is the main mode that occurs during ASYN conferences, and this in turn causes psychological stress. Statistics show the prevalence of a high incidence of complicated plural talks and a low response rate exists as the main factors preventing smooth human-to-human communication. Furthermore, comparing the response delays in face-to-face LT (Tf) and machine-mediated MT (Tm), human communication delay is significantly extended by the effects of initial mechanical delays. Therefore, cognitive intimacy of media is clearly affected by the existence of physical distance.