Direct Digital Frequency Synthesis Based on a Two-Level Table-Lookup Scheme

2006 ◽  
Vol 45 (3) ◽  
pp. 153-160 ◽  
Author(s):  
Sau-Gee Chen ◽  
Jen-Chuan Chih ◽  
Jun-Yi Chou
Keyword(s):  
Frequency Synthesis ◽  
Direct Digital Frequency Synthesis ◽  
Table Lookup ◽  
Digital Frequency

Frequency Conversion Type Ultrasonic Power Based on DSP Control Technology Research

2013 ◽  
Vol 442 ◽  
pp. 349-353 ◽  
Author(s):  
Chang You Li ◽  
Ming Ming Jia ◽  
Wen Hua Wang
Keyword(s):  
Embedded System ◽  
Power Supply ◽  
Frequency Conversion ◽  
Ultrasonic Power ◽  
Frequency Synthesis ◽  
Direct Digital Frequency Synthesis ◽  
Frequency Tracking ◽  
Digital Frequency ◽  
Frequency Changes ◽  
Dsp Control

The introduction of the direct digital frequency synthesis (DDS) technology in the field of communication is against the traditional ultrasonic machining power supply which does not have the multi-frequency tracking shortcomings to build a frequency conversion type ultrasonic power. Frequency conversion type ultrasonic power supply is based on DSP embedded system and adopts direct digital frequency synthesis (DDS) technology combined with a software phase locked frequency of composite frequency tracking scheme to realize automatic search transducer resonance frequency and frequency automatic tracking function which can response the different characteristics of the transducer dynamical; With the use of phase shift control power-principle to realize the output power regulating function when the frequency changes and reduce the switching power loss; It provides an important reference for the design of new frequency conversion type ultrasonic power.

Biomaterial Impedance Analyzer Based on Digital Auto Balancing Bridge

2011 ◽  
Vol 291-294 ◽  
pp. 1259-1262
Author(s):  
Nan Li ◽  
Yi Nan Wang ◽  
Hong Shan Nie ◽  
Hong Qi Yu ◽  
Hui Xu
Keyword(s):  
Bridge Circuit ◽  
Design Method ◽  
Circuit Simulation ◽  
Low Frequency ◽  
Operational Amplifiers ◽  
Frequency Synthesis ◽  
Direct Digital Frequency Synthesis ◽  
Impedance Analyzer ◽  
Digital Frequency ◽  
Phase Sensitive

This paper presents the design method of a novel biomaterial impedance analyzer based on digital auto balancing bridge method. The system hardware mainly consists of FPGA, ADC, DACs and operational amplifiers. Many DSP algorithms such as direct digital frequency synthesis (DDS), digital phase sensitive demodulation (DPSD), digital modulation and digital filter are implemented in FPGA to realize the auto balancing function of the bridge circuit. Simulation results show that the system has good performance from low frequency to 10MHz. It is suitable for EIS application in biomaterial analysis.

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