Digital to analog conversion device which decreases low level high frequency noise

摘要

A system and method for the conversion of digital signals to analog signals increases the resolution of the output analog signal beyond the analog quantization size associated with the given input digital word length. The rate of change of the Least Significant Bits (LSB)is detected. The "square waves" produced by changes in the polarity of the LSB correspond to low amplitude signals comprising audible high frequency components. The high frequency noise associated with these detected low signal levels is attenuated by digital low pass filters of varying cut-off frequencies at the output stage. This creates a signal of a resolution higher than the step size inherent in the length of the input digital word, and reduces high frequency noise at low signal amplitudes, resulting in a smooth analog output signal.