Patent ID: 7592941

Claim:
A signal processing apparatus comprising: analog-to-digital conversion means for performing a first delta sigma modulation process of generating a digital signal having a predetermined sampling frequency and a predetermined quantization bit rate of one or more bits based on an input analog signal; signal processing means including a digital filter to allow a delay time between input and output to be restricted within a predetermined range and having a predetermined characteristic for outputting a digital signal having a sampling frequency of n×Fs where n is a natural number and Fs is a predetermined reference sampling frequency and a predetermined quantization bit rate of a bits where a is a natural number greater than one based on the digital signal generated by said analog-to-digital conversion means; and digital-to-analog conversion means including a part for performing a second delta sigma modulation process for outputting a digital signal having a sampling frequency of n×Fs and a predetermined quantization bit rate of b bits where b is a natural number greater than zero and less than a based on a digital signal outputted from said signal processing means.