Second order digital filter requiring only one sigma delta modulator

摘要

A 2nd order digital filter requiring only one sigma delta modulator is created by implementing (1) a 2nd order feedforward term created by the cascade of two 1st order elements; (2) a 2nd order feedback term created by the cascade of two 1st order elements; and (3) another 2nd order feedback term created by the cascade of two more 1st order elements to eliminate the need for another sigma delta modulator to provide a 2nd order filter. Thus, for the mere "cost' of additional feedback loops, which are small in comparison with the size and complexity of another sigma delta modulator, a second sigma delta modulator is not necessary to implement a 2nd order digital filter in accordance with the principles with the present invention.