基于FPGA的正弦波PWM信号发生器的设计

Design of Sine-Wave PWM Signal Generator Based on FPGA

采用Altera公司的Cyclone系列FPGA为数字平台,利用Quartus II6.0已有的模块在FPGA中设计出了PWM信号发生器,整个系统可以实现频率、幅度均可调的信号输出。在产生某一频率信号时,让采样脉冲的周期保持不变,在每一个采样周期内改变一次占空比,改变的规律按正弦表变化;在产生高低不同频率的信号时,为了降低对滤波电路的复杂度,采用插空法使得输出的PWM波频率恒定。经过验证,设计系统的输出信号具有以下特点:稳定性和平滑性均较好,相比传统的信号产生方式,具有较高的频率分辨率,且易于实现频率幅度的数控调制,输出信号频率在1 Hz～1 MHz可调。

Design uses ALTERA＇s Cyclone series FPGA as digital platform, and uses Quartus Ⅱ 6.0 existing module to de-sign the PWM signal generator. Finally system can achieve adjustable frequency and amplitude output signal. Generating a certain frequency signal, the sampling pulse period remains constant, in each sampling period change a duty according to sine table. In order to reduce the complexity of the filter circuit, using interpolation method to make the frequency of the output PWM wave constant. After verification, the design system output signal has the following characteristics： good sta-bility and smoothness, compared to traditional signal generation methods, with high frequency resolution, and easy to imple- ment adjustable frequency and amplitude digital modulation, output signal frequency can be 1 Hz - 1 MHz adjustable.