Hardware Reduction in Digital Delta-Sigma Modulators via Bus-Splitting and Error Masking—Part II: Non-Constant Input

In this two-part paper, a design methodology for hardware reduction in digital delta-sigma modulators (DDSMs) based on bus-splitting and error masking is presented. Part I addresses Multi stAge noise SHaping (MASH) DDSMs with constant inputs; Part II focuses on error feedback modulators (EFMs) with time-varying inputs. In this paper, we address EFMs with DC inputs plus additive input least significant bit (LSB) dithering and show how hardware reduction can be achieved with minimal degradation of the output spectrum. We also address EFMs with sinusoidal inputs and show how bus-splitting and error masking techniques can be used to obtain a trade-off between the modulator complexity and the achievable signal-to-noise ratio.