Designed For Rectangular Bridge Signal Generator

Quardrature bridge plays a very important part in metrology area, it is mainly used to implement non-similar comparison of impedance measurement, quardrature bridge has varies structure, but no matter how the structure is,a pair of equal amplitude and phase difference of 90 quardrature voltage source is required.Direct digital frequency synthesizer (DDS),compared with traditional frequency synthesizer,can be easily adjusted to the phase,furthermore,it has high frequency resolution,and fast frequency switching,it can maintaine continuous phase in change of frequency, it is easy to implement frequency, phase and amplitude modulation.These characteristics of DDS make it very suitable quardrature bridge voltage signal source.This paper discusses the DDS usage at quardrature bridge measurement,and compared with traditional quardrature voltage sourse.Then introduced the basic working principle and structure, and finally introduces the hardware and software system design and experimental results are presented.In the system design process, this paper set Altera FPGA chip which named EP3C25Q240C8 as the core, using QUARTUSⅡand hardware description language Verilog HDL to design a frequency, phase, amplitude adjustable signal generator.Detail the architecture of the signal generator and conducted hardware and software design and implementation of specific circuits.Experimental results show that the system performance reached the design requirements, and is simple to use and has high integration,etc.