Idle-tone-free mismatch-shaping encoders

摘要

A technique to suppress idle tones in any mismatch-shaping encoder for use with a unit-element digital-to-analog converter. The arbitrary mismatch-shaping encoder provides a first set of signals which normally are intended to control directly the unit elements. A scrambler is used to interchange the first set of signals, thereby generating a second set of signals which are used to control the unit elements. The scrambler interchanges the signals as a function of a selector signal. A detecting circuit is used to evaluate in which clock cycles the unit elements have been used equally often. When this occurs, the selector signal is randomly assigned a new value in the following clock cycle.