Development of LXI Arbitrary Waveform Generator
|School||Harbin Institute of Technology|
|Course||Instrument Science and Technology|
|Keywords||LXI Arbitrary Waveform Generator DDS FPGA|
A LXI arbitrary waveform generator (AWG) is studied in this thesis. AWG is a kind of signal source with the development of computer technology and microelectronics technology applied in measuring instruments. It can be easily formed into a LXI automatic test system with other LXI instruments as foundation stimulation.This thesis adopts direct digital synthesis (DDS) as an overall plan and gives the specific scheme and the selection of components such as DAC, RAM, and operational amplifier of AWG after reading lots of technical reference literature. The entire hardware design is divided into two parts: LXI interface circuit and AWG functional circuit.First, an embedded ARM microprocessor is chosen as the controller in the design of AWG interface circuit, which, achieved communication between host computer and AWG by making full use of ARM’s high operation speed, integration and resource-rich features.Secondly, a piece of FPGA which improved the overall integration is used as the carrier of digital circuit in the AWG functional circuit design. The interface decoding module, the system D/A control module and the waveform generate control module is designed in QuartusⅡintegrated development environment with Verilog HDL which contribute to the high reliability and flexibility of the digital circuit. In addition, a 32-bit phase accumulator raises the output signal frequency resolution. In the design of the filter, a combination of filter technology (Elliptic filter, Bessel filter) is used in filtering different signals in order to improve the performance of the output signal. In the square wave generate circuit, the duty cycle accuracy and the quality of square wave signal are improved by using an analog output voltage switch.Finally, in arbitrary waveform generator software design, Boa is used as embedded Web server to achieve the control method of Web-based interface, and IVI-COM driver is introduced. This thesis introduces the output signal amplitude flatness testing methods and analyzes the error of AWG. Tests have demonstrated that all the functions and specifications of this LXI AWG reach the requirements of design.