The Optimization Design And Realization Of Delta-sigma Modulator For All-digital Transmitter

With the fast development of wireless communication technology,the wireless communication devices are gradually in direction of high efficiency and low consumption.As the core of wireless communication device,the wireless transmitter is valued particularly.Based on software radio technology,all-digital transmitter has the advantage of high efficiency,low power dissipation,miniaturization,and so on.And it is flexibly compatible with the demand of many different communication technology standards by changing software configurations on a hardware system,which is of great importance for constant evolving and changing wireless communication industry especially.The digital up-converter circuit is a key component of all-digital transmitter,which is also one part of restriction to the performance of all-digital transmitter.This paper has further study on the fundamental architecture of digital up-converter circuit in all-digital transmitter.And analyze comparatively the current digital up-converter circuit solution,as well as its disadvantage.And based on the delta-sigma modulator,a new design of all-digital up-converter circuit is proposed in this paper.The circuit,which are mainly composed of interpolation filters,delta-sigma modulators,word generator and high speed serial transmitter,could achieve the function of up-converting the base-band signal to higher RF frequency.Meanwhile,in order to improve the performance of the digital up-converter,The generalized Kalman-Yakubovich-Popov lemma of the control theory is introduced to optimize the delta-sigma modulator in this paper,which can improve the signal-to-noise ratio of output signal of the digital up-converter circuit by loop distribution algorithm.The main work of this paper is as follow:1)use the algorithm simulation tool and hardware simulation tool to do the tests on every module of the digital up-converter circuit respectively.2)do the system level simulation after cascading and combining those modules to form the digital up-converter system.3)create the digital up-converter circuit in Quartus II software platform by Verilog HDL.4)compile and download the circuit to hardware platform offered by Arria V GX Starter Kit for project running,and testing the output signal of the digital up-converter circuit with the help of mixing domain oscilloscope.According to the result of simulation,the algorithm for optimizing the delta-sigma modulator is available.And the result of hardware testing proves that the digital up-converter circuit designed in this paper could work properly,converting the base-band signal to higher RF frequency,like 907.2MHz,but reach the stop band attenuation of the output signal into 38dB.The result of this research provides a reference to the design scheme and make a reference on implementation method for the wireless communication devices,which has a certain value on the theory and application aspects in some degree.