1.6 GHz 24位4阶Σ-Δ小数分频频率合成器

A 1.6 GHz Fractional-N Frequency Synthesizer with a 24-b 4^(th)-Order Σ-Δ Modulator

介绍了一种3 V 0.35μm BiCMOS工艺实现的1.6 GHz小数分频频率合成器。它采用新型的24位4阶Σ-Δ调制结构数字调制器,以减少频率合成器的带内相位噪声、锁定频率切换时间,在获得高达20 MHz鉴相频率的同时,能达到小于1 Hz的频率分辨率。仿真结果表明,它的锁定范围是1.615~1.675 GHz,环路带宽100 kHz,带内相位噪声低于-90 dBc/Hz,锁定频率切换时间小于25μs,可以很好地满足个人手持电话系统PHS标准的应用。该电路功耗为20 mW,芯片面积1.7 mm×0.8 mm,其中,Σ-Δ调制部分所占面积为1 mm×0.4 mm。

A 1.6 GHz ∑-△ fractionabn frequency synthesizer is presented, which is implemented in 3-V 0. 35-μm BiCMOS process. A novel 24-b fourth-order ∑-△ modulator is employed to achieve low in-band phase-noise, agile switching, and fine frequency resolution less than 1Hz with 20 MHz reference frequency has been achieved. Simulation results show that the proposed system has a rapid switching time of 25μs, which meets the requirements of the personal mobile system（PHS） standard. The synthesizer has a 1.8% frequency tuning range from 1. 615 GHz to 1. 645 GHz. It dissipates 20 mW of power and occupies an active area of 1.7 mm×0. 8 mm including 1 mm × 0. 4 mm∑-△ modulator.