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Article
Publication date: 3 February 2020

Hamidreza Ghanbari Khorram and Alireza Kokabi

Several ultra-low power and gigahertz current-starved voltage-controlled oscillator (CSVCO) circuits have been proposed and compared here. The presented structures are based on…

Abstract

Purpose

Several ultra-low power and gigahertz current-starved voltage-controlled oscillator (CSVCO) circuits have been proposed and compared here. The presented structures are based on the three-stage hybrid circuit of the carbon nanotube field-effect transistors (CNTFETs) and low-power MOSFETs. The topologies exploit modified and compensated Schmitt trigger comparator parts to demonstrate better consumption power and frequency characteristics. The basic idea in the presented topologies is to compensate the Schmitt trigger comparator part of the basic CSVCO for achieving faster carrier mobility of the holes, reducing transistor leakage current and eliminating dummy transistors.

Design/methodology/approach

This study aims to propose and compare three different comparator-based VCOs that have been implemented using the CNTFETs. The considered circuits are shown to be capable of delivering the maximum 35 tuning frequency in the order of 1 GHz to 5 GHz. A major power thirsty part of the high-frequency ring VCOs is the Schmitt trigger stage. Here, several fast and low-power Schmitt trigger topologies are exploited to mitigate the dissipation power and enhance the oscillation frequency.

Findings

As a result of proposed modifications, more than one order of magnitude mitigation in the VCO power consumption with respect to the previously presented three-stage CSVCO is reported here. Thus, a VCO dissipation power of 3.5 µW at the frequency of 1.1 GHz and the tuning range of 26 per cent is observed for the well-established 32 nm technology and the supply voltage of 1 V. Such a low dissipation power is obtained around the operating frequency of the battery-powered cellular phones. In addition, using the p-carrier mobility compensation and enhancing the rise time of the Schmitt trigger part of the CSVCO, a maximum of 2.38 times higher oscillation frequency and 72 per cent wider tuning range with respect to Rahane and Kureshi (2017) are observed. Simultaneously, this topology exhibits an average of 20 per cent reduction in the power consumption.

Originality/value

Several new VCO topologies are presented here, and it is shown that they can significantly enhance the power dissipation of the GHz CSVCOs.

Details

Circuit World, vol. 46 no. 3
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 9 August 2021

Heydar Esmaeili, Alireza Isfandyari-Moghaddam and Mehdi Alipour Hafezi

This paper aims to draw a roadmap for the presence of Iranian academic libraries in the cloud infrastructure.

Abstract

Purpose

This paper aims to draw a roadmap for the presence of Iranian academic libraries in the cloud infrastructure.

Design/methodology/approach

This research attends an applied-development one that is a part of developmental research due to its conceptual expansion, foresight and roadmap for the presence of cloud-based academic libraries and finally, becoming cloud libraries. Because of providing a roadmap template, the presence of academic digital libraries in the cloud and becoming a cloud library is applied research. Because of providing a roadmap template, academic digital libraries’ presence in the cloud and becoming a cloud library is one of the applied research areas. The statistical population of this research includes all Iranian digital academic libraries. There were 64 digital libraries out of which 59 libraries participated in completing the questionnaire.

Findings

Preliminary results from used Delphi method’s first round which was considered by 59 experts were identified typically and descriptive after appropriate component classification and editing. After identifying these factors, each of the roadmap levels in the third stage and the degree of relevance approved by the experts were reviewed and the most critical and relevant factors were identified as key components of the roadmap for the presence of cloud-based academic libraries and becoming cloud libraries. At this stage, they were selected as 24 factors, including seven factors for the first layer, eight factors for the second layer and nine factors for the third layer.

Originality/value

By introducing a roadmap for the presence of academic digital libraries in the cloud context, they will promote more and better interaction between academic libraries to offer services to users anytime and anywhere.

Details

Global Knowledge, Memory and Communication, vol. 71 no. 6/7
Type: Research Article
ISSN: 2514-9342

Keywords

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