Details
![Liqun Feng Headshot](https://confcats-catavault.s3.amazonaws.com/CATAVault/ieeecass/master/files/styles/cc_user_photo/s3/user-pictures/12311.jpg?h=df1b6c88&itok=Oee7iMgp)
- Affiliation
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AffiliationTsinghua University
- Country
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CountryChina
This paper describes an efficient way to reduce the quantization noise of delta-sigma fractional-N PLLs by using an injection-locked oscillator (ILO) in the feedback path. For further noise reduction, the use of cascaded ILOs is proposed. Behaving like a type-I high-order PLL, the cascaded ILOs effectively suppress the quantization noise like a high-order phase-domain low-pass filter (PDLPF). We show that the proposed ILO-based PDLPF significantly improves the out-of-band phase noise for wideband fractional-N PLLs as well as the in-band phase noise for fractional-N bang-bang PLLs (BBPLLs). Simulation results show that a delta-sigma fractional-N BBPLL with a 3-stage ILO can achieve the in-band noise reduction of 25dB without having a nested PLL.