Mohammad Sadegh Mirzajani Darestani, Mohammad Bagher Tavakoli and Parviz Amiri
The purpose of this paper is to propose a new design strategy to enhance the bandwidth and efficiency of the power amplifier.
Abstract
Purpose
The purpose of this paper is to propose a new design strategy to enhance the bandwidth and efficiency of the power amplifier.
Design/methodology/approach
To realize the introduced design strategy, a power amplifier was designed using TSMC CMOS 0.18um technology for operating in the Ka-band, i.e. the frequency range of 26.5-40 GHz. To design the power amplifier, first, a power divider (PD) with a very wide bandwidth, i.e. 1-40 GHz, was designed to cover the whole Ka-band. The designed Doherty power amplifier consisted of two different amplification paths called main and auxiliary. To amplify the signal in each of the two pathways, a cascade distributed power amplifier was used. The main reason for combining the distributed structure and cascade structure was to increase the gain and linearity of the power amplifier.
Findings
Measurements results for designed power dividers are in good agreement with simulations results. The simulation results for the introduced structure of the power amplifier indicated that the gain of the proposed power amplifier at the frequency of 26-35 GHz was more than 30 dB. The diagram of return loss at the input and output of the power amplifier in the whole Ka-band was less than −8dB. The maximum power-added efficiency (PAE) of the designed power amplifier was 80%. The output P1dB of the introduced structure was 36 dB and the output power of the power amplifier was 36 dBm. Finally, the IP3 value of the power amplifier was about 17 dB.
Originality/value
The strategy presented in this paper is based on the usage of Doherty and distributed structures and a new wideband power divider to benefit from their advantages simultaneously.
Details
Keywords
Hadi Dehbovid, Habib Adarang and Mohammad Bagher Tavakoli
Charge pump phase locked loops (CPPLLs) are nonlinear systems as a result of the nonlinear behavior of voltage-controlled oscillators (VCO). This paper aims to specify jitter…
Abstract
Purpose
Charge pump phase locked loops (CPPLLs) are nonlinear systems as a result of the nonlinear behavior of voltage-controlled oscillators (VCO). This paper aims to specify jitter generation of voltage controlled oscillator phase noise in CPPLLs, by considering approximated practical model for VCO.
Design/methodology/approach
CPPLL, in practice, shows nonlinear behavior, and usually in LC-VCOs, it follows second-degree polynomial function behavior. Therefore, the nonlinear differential equation of the system is obtained which shows the CPPLLs are a nonlinear system with memory, and that Volterra series expansion is useful for such systems.
Findings
In this paper, by considering approximated practical model for VCO, jitter generation of voltage controlled oscillator phase noise in CPPLLs is specified. Behavioral simulation is used to validate the analytical results. The results show a suitable agreement between analytical equations and simulation results.
Originality/value
The proposed method in this paper has two advantages over the conventional design and analysis methods. First, in contrast to an ideal CPPLL, in which the characteristic of the VCO’s output frequency based on the control voltage is linear, in the present paper, a nonlinear behavior was considered for this characteristic in accordance with the real situations. Besides, regarding the simulations in this paper, a behavior similar to the second-degree polynomial was considered, which caused the dependence of the produced jitter’s characteristic corner frequency on the jitter’s amplitude. Second, some new nonlinear differential equations were proposed for the system, which ensured the calculation of the produced jitter of the VCO phase noise in CPPLLs. The presented method is general enough to be used for designing the CPPLL.
Details
Keywords
Bahrampour Hamid, Askari Mohammad Bagher, Bahrampour Mohammad Reza and Bahrampour Mahboubeh
This paper aims to identify and introduce areas in Kerman with a very high potential for produce energy from renewable energy. In this paper, with studying renewable energy…
Abstract
Purpose
This paper aims to identify and introduce areas in Kerman with a very high potential for produce energy from renewable energy. In this paper, with studying renewable energy resources of the world and Iran, and with the introduction of renewable energy resources in Kerman Province and its counties as a proper supplier of energy in Iran and regions. At the end of this discussion, it is seen that the positive impact of clean energies on the economy, the environment and the health of the region and the country and the potential of the Kerman Province in this rare energy place are considered well.
Design methodology/approach
To study the energy consumption in Iran and based on universal reports, this area is the largest renewable energy production region in Iran.
Findings
Currently, electricity used in Kerman is nearly 2,000 MW, while the capacity of production is 1,500 MW which is almost the share of renewable energy in electricity production rate is zero. With regard to industrial development plans in Kerman Province, 5,000 MW of electricity will be needed in the near future, so the province will face an energy crisis. Iran is also a developing country and economy; agriculture and the production of this country is extremely dependent on energy and electricity, and it seems that using renewable energy sources is a way to prevent an energy crisis in the country.
Originality/value
This paper introduces the Kerman Province and examines the potential of this province as a massive source of energy in Iran and the world. Specific qualifications of this region include the climate variability, existing water dams, suitable areas for utilization of biomass and the high potential that this area has for the development of geothermal energy. These qualifications all contribute to make this region a hub for great production of energy from renewable energy sources in Iran.
Details
Keywords
Hossein Mollashahi, Mohammad Bagher Fakhrzad, Hasan Hosseini Nasab and Hassan Khademi Zare
Nowadays, the topic of supply chain network design has gained significant attention as a critical area within the field of supply chain management. Researchers have dedicated…
Abstract
Purpose
Nowadays, the topic of supply chain network design has gained significant attention as a critical area within the field of supply chain management. Researchers have dedicated their studies to exploring market competitiveness and pursuing greater benefits. This paper presents a multi-objective mathematical model aimed at designing a competitive and sustainable closed-loop supply chain network specifically for perishable products. The proposed model takes into account the competition between two supply chains, considering various factors such as environmental impacts, social performance and resilience.
Design/methodology/approach
To address the competitive nature of this model, this study introduces a two-stage approach. In the initial stage, this study uses a game theory approach to determine equilibrium values for competitive decisions. This allows establishing a fair and balanced playing field between the two supply chains. Subsequently, due to the complexity of the proposed model, this study uses a multi-objective metaheuristic algorithm based on the Non-dominated Sorting Genetic Algorithm. This algorithm serves as a robust computational tool to effectively solve the network design problem and optimize the desired objectives.
Findings
To evaluate the effectiveness of the proposed model and solution approach, this study provides a numerical example. Through graphical and statistical analysis, this study assesses the performance of the model and its ability to achieve the desired objectives. The results and charts obtained demonstrate the strong performance and efficacy of the proposed model in effectively addressing the challenges associated with designing a competitive and sustainable closed-loop supply chain network for perishable products.
Research limitations/implications
By considering the various factors at play and incorporating them into the model, this study aims to contribute to the existing body of knowledge in supply chain management. The findings provide valuable insights into designing supply chain networks that not only enhance competitiveness but also promote sustainability.
Originality/value
This study represents one of the initial investigations into the evaluation of competitive supply chains, taking into account crucial factors such as environmental, social and resilience. A supply chain that considers these factors can attain greater durability and competitiveness compared to other supply chains.