摘要
This paper presents a 25-MHz fully-integrated digitally controlled crystal oscillator（DCXO） with automatic amplitude control（AAC）.The DCXO is based on Colpitts topology for one-pin solution.The AAC circuit is introduced to optimize the phase noise performance.The automatic frequency control is realized by a 10-bit thermometer-code segmental tapered MOS capacitor array,ensuring a～35 ppm tuning range and～0.04 ppm frequency step.The measured phase noise results are-139 dBc/Hz at 1 kHz and-151 dBc/Hz at 10 kHz frequency offset,respectively.The chip consumes 1 mA at 1.8V supply and occupies 0.4 mm^2 in a 0.18-μm CMOS process.
This paper presents a 25-MHz fully-integrated digitally controlled crystal oscillator（DCXO） with automatic amplitude control（AAC）.The DCXO is based on Colpitts topology for one-pin solution.The AAC circuit is introduced to optimize the phase noise performance.The automatic frequency control is realized by a 10-bit thermometer-code segmental tapered MOS capacitor array,ensuring a～35 ppm tuning range and～0.04 ppm frequency step.The measured phase noise results are-139 dBc/Hz at 1 kHz and-151 dBc/Hz at 10 kHz frequency offset,respectively.The chip consumes 1 mA at 1.8V supply and occupies 0.4 mm^2 in a 0.18-μm CMOS process.
基金
Project supported by the National Natural Science Foundation of China(No.60876019)
the National S&T Major Project of China(No. 2009ZX0131-002-003-02)
the Shanghai Rising-Star Program,China(No.09QA1400300)
the National Scientists and Engineers Service for Enterprise Program,China(No.2009GJC00046).
