Fpga Based Sigma Delta Modulator Design For Biomedical Application Using Verilog Hdl

Abstract: The present invention provides a delta-sigma modulator for converting an external analog signal to a digital output signal. The delta-sigma modulator comprises a first filter circuit, a second filter circuit, a one-bit quantization, a multi-bit quantization, a digital-to-analog converter, and a digital filter. The first filter circuit outputs a first analog signal according to the external analog signal and a one-bit output signal. The second filter circuit outputs a third analog signal according to the first analog signal and a second analog signal. The one-bit quantization converts the third analog signal into the one-bit output signal. The multi-bit quantization converts the third analog signal into a multi-bit output signal. The digital-toanalog converter comprises a plurality of capacitors, and determines the number of capacitors to be charged according to the multi-bit output signal, then selects the capacitors to be charged in a predetermined turn and charges the capacitors. When the digital-to-analog converter receives the alternate multi-bit output signal, the digital-to-analog converter selects the capacitors in a turn reversing to the predetermined turn and charges the selected capacitors, which number corresponds to the multi-bit output signal, to generate the second analog signal. The digital filter converts the one-bit output signal and the multi-bit output signal to the digital output signal

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