基于高阶单比特Σ△调制器的频率综合器

High-order single-bitΣ△modulator in frequency synthesizer

本文介绍了高阶单比特Σ△调制器在小数分频频率综合器中的应用。普通小数分频频率综合器容易产生很大的杂散频率,采用Σ△调制器可以有效消除杂散频率降低相位噪声。由于多比特MASH结构的非线性,这里采用单比特高阶Σ△调制器(CIFB),最后提出实现电路。

In this paper, a fractional-N frequency synthesizer based on high-order single-bit ∑△ modulator is introduced. Typical fractional-N frequency synthesizer suffers from spurious frequency. The use of ∑△ modulator results in a better phase noise and reduced spurious frequency. As the nonlinearity of multi-bit MASH structure, high-order single-bit ∑△ modulator （CIFB） is adopted, and practical circuits based on proposed concept are given.