Design of Direct Digital Synthesizer Based on FPGA

2013 ◽  
Vol 748 ◽  
pp. 829-832
Author(s):  
Cai Hong Liu ◽  
Jin Shui Ji ◽  
Ai Qin Qi ◽  
Wei Zhang
Keyword(s):  
Phase Locked Loop ◽  
Frequency Synthesizers ◽  
Direct Digital Synthesizer ◽  
Digital Frequency ◽  
High Bandwidth ◽  
The Difference

Traditional designs of high bandwidth frequency synthesizers employ the use of a phase locked-loop. A direct digital synthesizer (DDS) provides many significant advantages over the PLL approaches. The thesis emphasizing discusses the designing of DDS basing on FPGA. DDS is made up of the phrase accumulator and sine ROM looking-up table, which is realized by functional EAB chip. And through setting different initial accumulator value and initial phrase value, the difference of phrase between the two sine signals can be changed. As a result, two serials of sine signals with changeable digital frequency, phrase and magnitude are produced. The simulate results show that logic in FPGA is consistent with the requirements.

scholarly journals Analysis of Noise Characteristics of Multichannel Systems of the Formation of Signals of Georadars with Synthesized Aperture

2018 ◽  
Vol 2018 ◽  
pp. 1-7
Author(s):  
Oleg R. Kuzichkin ◽  
Dmitriy I. Surzhik ◽  
Gleb S. Vasiliev ◽  
Igor A. Kurilov ◽  
Nikolai V. Dorofeev
Keyword(s):  
Frequency Synthesizer ◽  
Phase Locked Loop ◽  
Frequency Synthesizers ◽  
Automatic Compensation ◽  
Direct Digital Synthesizer ◽  
Reference Oscillator ◽  
Noise Characteristics ◽  
Hybrid Frequency ◽  
Multichannel Systems ◽  
Phase Distortions

The noise characteristics of multichannel systems of forming signals based on hybrid frequency synthesizers with automatic compensation of phase distortions of direct digital synthesizers, which are used in the composition of georadars with synthesized aperture, are investigated. It is established that the phase noise of the output signals of the formers at the 1 kHz detuning from the carrier oscillation at the output frequencies of the devices in the range from 500 to 3500 MHz is characterized by a level of minus 100 - minus 130 dB. In this case, the circuit of the signal former based on a hybrid frequency synthesizer with direct digital synthesizer as a reference oscillator of a phase locked loop is characterized by the worst noise characteristics but with the highest degree of autocompensation (about 13 dB). Conversely, the circuit of the signal former based on a hybrid frequency synthesizer with direct digital synthesizer as a support generator of the phase-locked loop has the best phase noises level from the considered variants of devices and least degree of autocompensation (about 6 dB).

scholarly journals DIRECT DIGITAL FREQUENCY SYNTHESIZER IN THE RESIDUE NUMBER SYSTEM

2019 ◽  
pp. 307-315
Author(s):  
Oleksiy Polikarovskykh ◽  
Vasyl Melnychuk ◽  
Ihor Hula ◽  
Lesia Karpova
Keyword(s):  
Frequency Synthesizer ◽  
Number System ◽  
Residue Number System ◽  
Frequency Synthesizers ◽  
Direct Digital Synthesizer ◽  
Number Systems ◽  
Digital Frequency ◽  
Residue Number ◽  
Speed Up ◽  
Direct Digital Frequency Synthesizers

The principles of construction and operation of direct digital frequency synthesizers are considered in order to speed up computational operations using Residue Number System. The problems of forming the output signals are considered. The specifics of the implementation of the operation of direct and reverse transformations from positional to non-positional number systems are described. A mathematical model of a synthesizer with a phase accumulator in a Residue Number System is considered. Methods for converting from RNS (Residue Number System) to binary system for problematic operations are considered. The design of a DDS (Direct Digital Synthesizer) with a phase accumulator in a Residue Number System and a converter to an analogue signal form is proposed without the use of slow ROM (Read Only Memory). The article deals with the issues of efficiency of the crystal area of the synthesizer and the reduction of the delays in the formation of the output signal.

Phase-Locked Loop Frequency Synthesizers

1998 ◽  
pp. 15-47
Author(s):  
J. Craninckx ◽  
M. Steyaert
Keyword(s):  
Phase Locked Loop ◽  
Frequency Synthesizers

Implementation of types of VCO

2021 ◽  
Vol 9 (8) ◽  
pp. 2972-2678
Author(s):  
Akshata O. Kattimani
Keyword(s):  
Frequency Shift ◽  
Building Block ◽  
Relaxation Oscillator ◽  
Phase Locked Loop ◽  
Frequency Synthesizers ◽  
Ring Oscillator ◽  
Electronic Systems ◽  
Basic Building Block ◽  
Colpitts Oscillator ◽  
Shift Keying

Abstract: A Voltage Controlled Divider (VCO) is a basic building block in most of the electronic systems. Phase-locked loop (PLL), tone synthesizers, Frequency Shift Keying (FSK), frequency synthesizers, etc make use of VCO’s to generate an oscillating frequency that can be decided with the help of components. Voltage Controlled Divider can be implemented for analog applications. The project proposes three types of VCO using Electric tool and LT Spice XVII tool. The three VCO’s that are implemented are CMOS Ring Oscillator, Colpitts Oscillator and Relaxation Oscillator. These circuits generate two oscillating frequencies that is decided by the circult components. Keywords: Voltage Controlled Divider (VCO), CMOS Ring Oscillator, Colpitts Oscillator, Relaxation Oscillator, oscillating frequency.

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