Spur Performance and Relative Implementation Costs of MASH and ENOP Digital ΔΣ Modulators

The Digital Modulator (DDSM) is an integral component in fractional-N Phase-Locked Loops (PLLs) for frequency synthesis where it is used to achieve the fractional part of the frequency. Compared to a conventional DDSM, which is infamous for exhibiting spurious tones, the Enhanced Non-Linearity Induced Noise Performance (ENOP) DDSM can be designed so that it does not produce spurious tones when used in a PLL with a polynomial nonlinearity. This paper focuses on quantifying the relative implementation costs of conventional DDSMs and ENOP DDSM variants.