High performance stereo bit-stream DAC with digital filter

A bit-stream converter is described whose main functions are digital filtering and oversampling, noise shaping, and code conversion to generate a 1-b data stream, and 1-b D-to-A (digital-to-analog) conversion to generate an analog signal from the 1-b stream. Four operational amplifiers for the third-order low-pass filter are also integrated (two for each channel). Inherent in the multibit D/A conversion system is nonlinearity due to mismatching of conversion elements. The bit-stream conversion technique overcomes this by using a 1-b converter. The number of bits in a sample can be reduced to a single bit without loss of resolution by means of oversampling and noise shaping. The bit-stream D/A conversion technique can be implemented in standard CMOS technology. Inherent in the bit-stream conversion concept is the ability to achieve very high-quality sound. It is also well suited for total integration of DACs with other system functions using VLSI technologies.<
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