A phase noise filter for RF oscillators

In this work, a phase noise reduction architecture for standalone oscillators is presented. The oscillator phase is divided and a voltage is generated by a type-I phase detector, which is compared with an ideal voltage to change the phase of the oscillator. Analysis shows that the loop parameters aid in phase noise suppression. The design is done in CMOS 90 nm technology for a 1 GHz ring oscillator. Post-layout simulations show that phase noise suppression is about 13 dB at 100 MHz offset for a division ratio of 2.