A successive requantizer, which serves as a replacement for a ΔΣ modulator in a fractional-N PLL or a DAC, and avoids spurious tone problems, thereby circumventing the tradeoffs that result from reliance on the common approach of making highly linear analog circuitry to avoid spurious tones. A successive requantizer fractional-N PLL of the invention has the potential to reduce power consumption and the cost of commercial communication devices. The successive requantizer performs digital quantization one bit at a time in such a way that the quantization noise can he engineered to have desirable properties such as non-linearity robustness. The successive requantizer is applicable to most high-performance digital communication systems, such as cellular telephone handsets and wireless local and metropolitan area network transceivers.