Rim Ayadi

An effective CMOS Charge Pump-Phase Frequency Detector Circuit for PLLs applications

Charge Pump controlled with three states of a Phase Frequency Detector is an essential building block of Phase Locked Loops (PLLs). Charge Pump-Phase Locked Loops are usually used in diverse applications, such as on chip clock synthesis, symbol timing recovery for serial data streams and generation of frequency agile high frequency carrier signals. This paper describes an effective structure of a Charge Pump (CP) and a Phase Frequency Detector (PFD) circuits which are the key blocks for the design of PLLs. The behavioral modeling has been synthesized from a hardware description language (VHDL-AMS). This CP-PFD circuit was designed with 0.35μm AMS CMOS technology. Electrical simulation results are shown using ADS platform.

Decision Tree Transformation for Knowledge Warehousing

Explicit knowledge extracted from data, formalized tacit knowledge from experts or even knowledge existing in business sources may be in several heterogeneous formal representations and structures: as rules, models, functions, etc. However, a knowledge warehouse should solve this structural heterogeneity before storing knowledge. This requires specific tasks of harmonizing. This paper first presents our proposed definition and architecture of a knowledge warehouse, and then presents some languages for knowledge representations as particular the MOT (Modeling with Object Types) language. In addition, we suggest a metamodel for the MOT, and a metamodel for the explicit knowledge obtained using decision trees technique. As we aim to represent knowledge having different modeling formalisms into MOT, as a unified model, then we suggest a set of transformation rules that assure the move from the decision tree source model into the MOT target model. This work is still in progress, it is currently completed with tranformations for additional.

Analysis of a Third-Order Charge-Pump Phase-Locked Loops used for Wireless Sensor Transceiver

The evaluation of integrated circuits such as Phase Locked Loops is a challenge in mixed-signal design. In most cases, these circuits are evaluated with electrical stimulations. To verify the proper operation of system before moving on to the design process, it is necessary to model these performances parameters with a hardware description language. At behavioral level, the performances of circuits are optimized without considering its transistor level structure. This paper, present an exact s-domain model analysis of a Third-Order Charge-Pump Phase-Locked Loops (CP-PLLs) used for wireless sensor transceiver using state equations of Phase Frequency Detector. Both the state equations and the transfer functions behavior modeling are described using this analysis. The linear state equations and s-domain transfer functions are provided. Critical advantage of illustrated methodology is a shortened PLL operating process due to the use of fastsimulating models at behavioral level. The analysis is verified using behavioral simulations with VHDL-AMS in Simplorer.

MOT Knowledge Model Integration Rules for Knowledge Warehousing

Abstract A knowledge warehousing process aims to build an intelligent decision support system. It collects, homogenizes, integrates and stores knowledge for a decision-making process. In this paper, we are interested in knowledge integration. More accurately, we propose an integration process for knowledge homogenized/modeled according to the MOT (Modeling with Object Types) knowledge model. This integration process consists of three ordered steps based on the type of schemas to integrate and their similarity. For this process, we define five integration rules based on semantic relationships between elements of MOT knowledge models, and then we develop an algorithm using these integration rules.

Design of an Effective Charge Pump-Phase Locked Loops Architecture for RF Applications

and mixed architectures design with high performance suffered from many difficulties due to low power supply, consumption, and the trend toward reducing the size of the circuit. Currently, these performances are considered one of the main constraints in analog design. Characterized and designed of mixed circuits such as Charge Pump-Phase Locked Loops (CP- PLLs) is a challenge in mixed-signal integrated circuits design. In this paper, an effective CMOS CP-PLLs architecture for RF applications that operates at a low power supply 2V into a large range frequency is presented. The proposed CP-PLLs architecture has two novel design blocks which are respectively Phase Frequency Detector (PFD) and Voltage Controlled Oscillator (VCO). The key advantage of the two novel designs is that uses a simple circuit, provide more stable operation compared with other structures recently used and reduce the chip area overhead. Also, the novel VCO design solved the problems caused by recent structures. The CP-PLLs is designed and evaluated using electrical simulator tolls (ADS) with 0.35μm AMS CMOS technology. Simulations results show a good performance and the effectiveness of the proposed structure.

Association Rules Transformation for Knowledge Integration and Warehousing

Knowledge management process is a set of procedures and tools applied to facilitate capturing, sharing and effectively using knowledge. However, knowledge collected from organizations is generally expressed in various formalisms, therefore it is heterogeneous. Thus, a Knowledge Warehouse (KW), which is a solution for implementing all phases of the knowledge management process, should solve this structural heterogeneity before loading and storing knowledge. In this paper, we are interested in knowledge normalization. More accurately, we firstly introduce our proposed architecture for a KW, and then we present the MOT (Modeling with Object Types) language for knowledge representation. Since our objective is to transform heterogeneous knowledge into MOT, as a pivot model, we suggest a meta-model for the MOT and another for the explicit knowledge extracted through the association rules technique. Thereafter, we define eight transformation rules and an algorithm to transform an association rules model into the MOT model.