Delta-sigma modulator with μ-synthesis and switching loop filter based on the linear gain

A delta-sigma modulator is one of systems used for an analog-to-digital converter. It is known that high signal-to-noise ratio will be obtained by making a high-order loop filter of the delta-sigma modulator. However, when input amplitude becomes large, a problem that the system becomes unstable occurs. This paper proposes a delta-sigma modulator combining the method of switching the loop filter by the change of the linear gain with the loop filters designed through a μ-synthesis. A stable range will spread out for large input amplitude by using the method of switching the loop filter. The effectiveness of the proposed method is confirmed by computer simulations.