STUDY ON SMALL-SIGNAL IMPEDANCE OF SINGLE-WALLED ZIGZAG CARBON NANOTUBES IN TERAHERTZ FREQUENCY REGIME

2013 ◽  
Vol 27 (21) ◽  
pp. 1350105 ◽  
Author(s):  
C. WANG ◽  
J. C. CAO
Keyword(s):  
Carbon Nanotubes ◽  
Differential Resistance ◽  
Small Signal ◽  
Analysis Method ◽  
Terahertz Frequency ◽  
Promising Candidate ◽  
Small Signal Analysis ◽  
Current Voltage ◽  
Frequency Regime ◽  
Signal Analysis Method

We theoretically study the static and dynamic transport properties of Mott–Gurney diodes based on semiconducting single-walled zigzag carbon nanotubes (CNTs). The electric field and velocity distribution of the diode under dc voltage is obtained by solving the steady-state drift-diffusion equations, which involve the negative differential velocity. The current–voltage characteristic of CNT diode exhibits a distinctive positive differential resistance. The high-frequency impedance is calculated with the small-signal analysis method. A major feature of the proposed CNT diode is that the bias- and tube index-dependent impedance show several negative windows in terahertz frequency range despite the positivity of the dc differential resistance. This property makes the CNT-based Mott–Gurney diode a promising candidate for the generation and amplification of terahertz signals within the desired frequency region.

scholarly journals On the Equivalence of the Switched Inductor and the Tapped Inductor Converters and its Application to Small Signal Modelling

Energies ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4806
Author(s):  
Jia Yao ◽  
Kewei Li ◽  
Kaisheng Zheng ◽  
Alexander Abramovitz
Keyword(s):  
Signal Analysis ◽  
Buck Converter ◽  
Small Signal ◽  
Analysis Method ◽  
Signal Model ◽  
Small Signal Analysis ◽  
Small Signal Model ◽  
Signal Modelling ◽  
Small Signal Modeling ◽  
Signal Analysis Method

Switched inductor (SI) converters are popular in applications requiring a steeper conversion ratio. However, these converters operate a twin inductor switching cell, which complicates the small-signal modeling. This paper proposes an expeditious small-signal analysis method to model the SI converters. The offered modeling approach is hinged on the analogy existing between the SI converters and certain Tapped Inductor (TI) converters. It is suggested here that by virtue of the analogy of the SI converters and TI converters the small-signal model of the SI converter is identical to that of its ideal TI counterpart. Hence, the recently developed Tapped Inductor Switcher (TIS) methodology can be applied to the modeling of the SI converters as well. As an example, the small-signal model of the Switched Inductor Buck converter is obtained. Theoretical analysis was confirmed by simulation and experimental results. In addition, several other SI converters and their TI counterparts are identified.

scholarly journals Design and Implementation of a High Step-Up DC-DC Converter Based on the Conventional Boost and Buck-Boost Converters with High Value of the Efficiency Suitable for Renewable Application

2021 ◽  
Vol 13 (19) ◽  
pp. 10699
Author(s):  
Tohid Rahimi ◽  
Md Rabiul Islam ◽  
Hossein Gholizadeh ◽  
Saeed Mahdizadeh ◽  
Ebrahim Afjei
Keyword(s):  
Duty Cycle ◽  
Signal Analysis ◽  
High Efficiency ◽  
Switching Frequency ◽  
Small Signal ◽  
Voltage Gain ◽  
Boost Converters ◽  
Small Signal Analysis ◽  
Current Voltage ◽  
Input Filter

This paper introduces a novel topology of the proposed converter that has these merits: (i) the topology of the converter is based on conventional boost and buck-boost converters, which has caused its simplicity; (ii) the voltage gain of the converter has provided higher values by the lower value of the duty cycle; (iii) due to the use of high-efficiency conventional topologies in its structure, the efficiency of the converter keeps its high value for a great interval of duty cycle; (iv) besides the increase of the voltage gain, the current/voltage stresses of the semiconductors have been kept low; (v) the continuous input current of this converter reduces the current stress of the capacitor in the input filter. It is worth noting that the proposed converter has been discussed in both ideal and non-ideal modes. Moreover, the operation of the converter has been discussed in both continuous/discontinuous current modes. The advantages of the converter have been compared with recently suggested converters. In addition, the different features of the converter have been discussed for different conditions. In the small-signal analysis, the appropriate compensator has been designed. Finally, the simulation and experimental results have been reported for 90 W output power, 90 V output voltage, 3-times voltage gain, and 100 kHz switching frequency.

scholarly journals A S-Type Bistable Locally-Active Memristor and Its Application in Oscillator Circuit

2021 ◽  
Author(s):  
Chunlai Li ◽  
Haodong Li ◽  
Wenwu Xie ◽  
Jianrong Du
Keyword(s):  
Active Region ◽  
Analog Circuit ◽  
Initial Conditions ◽  
Chaotic Oscillation ◽  
Hysteresis Loops ◽  
Analysis Method ◽  
Oscillator Circuit ◽  
Small Signal Analysis ◽  
Pinched Hysteresis ◽  
Signal Analysis Method

Abstract In this paper, a S-type memristor with tangent nonlinearity is proposed. The introduced memristor can generate two kinds of stable pinched hysteresis loops with initial conditions from two flanks of the initial critical point. The power-off plot verifies that the memristor is nonvolatile, and the DC V-I plot shows that the memristor is locally active with the locally-active region symmetrical about the origin. The equivalent circuit of the memristor, derived by small-signal analysis method, is used to study the dynamics near the operating point in the locally-active region. Owing to the bistable and locally-active properties and S-type DC V-I curve, this memristor is called S-type BLAM for short. Then, a new Wien-bridge oscillator circuit is designed by substituting one of its resistances with S-type BLAM. It find that the circuit system can produce chaotic oscillation and complex dynamic behavior, which is further confirmed by analog circuit experiment.

Negative small-signal impedance of nanoscale GaN diodes in the terahertz frequency regime

2007 ◽  
Vol 90 (14) ◽  
pp. 142117 ◽  
Author(s):  
V. N. Sokolov ◽  
K. W. Kim ◽  
V. A. Kochelap ◽  
P. M. Muntiian
Keyword(s):  
Small Signal ◽  
Terahertz Frequency ◽  
Frequency Regime
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