1. State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instruments, Tsinghua University, Beijing 100084, China
2. Astronaut Center of China, Beijing 100094, China
A 24-bit sigma-delta digital-to-analog converter (DAC) is used to produce high precision sinusoidal signals with low total harmonic distortion (usually less than -106 dB) for seismic data acquisition system self-tests. The key problem is to convert the sinusoid to a sigma-delta bit stream to drive the sigma-delta DAC. This paper presents a field-programmable gate array (FPGA) based bit stream generator which is composed of a sinusoidal data memory, an interpolation filter and a sigma-delta modulator. This paper focuses on the design and simulation methods for the interpolation filter and the sigma-delta modulator and the whole system implementation using the DSP Builder in FPGA. Tests show that the bit stream generator can drive a 24-bit sigma-delta DAC to produce a 31.25 Hz, 3.96 V peak-peak voltage sinusoidal signal with -121.0 dB total harmonic distortion and 111.4 dB signal-to-noise ratio, which meets the needs for seismic use. The design is simple, programmable and easy to implement.
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2014, Vol. 54 
),马骋1,熊剑平1,尹永利2
