Design and implementation of sigma-delta digital modulator based on FPGA

Digital modulation technology with low complexity and high precision is widely demanded in the industrial field. Traditional pulse width modulators (PWM) have problems such as insufficient precision, excessive noise, and weak adaptability. This article uses a Sigma-Delta digital modulator to replace the traditional PWM modulator. First of all, the sampling rate of the source determines the output accuracy of the modulator. When the source adoption rate is low, this solution improves the accuracy through upsampling. The input accuracy of the signal source is improved, thereby improving the output accuracy of the modulator. Secondly, to address the problem of excessive noise, this paper uses noise shaping technology and constructs a fourth-order CIFF structure Sigma-Delta modulator model through comparison. Then, based on The FPGA hardware platform has implemented the given Sigma-Delta modulation scheme in real time. The simulation and real-time implementation results show that using oversampling technology increases the Nyquist sampling rate by approximately 3dB, which is equivalent to an increase in the number of effective digits. 0.5 times, the oversampling rate is increased by 4 times in exchange for an increase in 1-bit resolution; at the same time, the experimental results show that the signal-to-noise-distortion ratio of using noise shaping technology is increased to 117.3dB, and the effective number of bits is increased to 117.3dB compared to not using noise shaping technology. 19.2 bits.