Accurate stability prediction of single-bit higher-order delta-sigma (Δ-Σ) modulators for speech codecs

Present approaches for predicting the stability of Delta-Sigma (Δ-Σ) modulators are mostly confined to DC inputs. This poses limitations as practical applications of Δ-Σ modulators involve a wide range of signals other than DC such as speech, audio and multiple sinusoids as is the case for synthetically generated speech or audio or any other signal, through the appropriate composition of multiple sinusoids. In this paper, a quasi-linear model that accurately predicts stability of single-loop 1-bit higher-order Δ-Σ modulators for multiple sinusoids is given. The results of this paper would enable optimization of the design of higher-order single-loop Δ-Σ modulators with increased dynamic ranges for various applications that deploy multiple sinusoidal inputs, as well as any general input signal constructed from multiple sinusoids.