Integrated Phase Locked Loop and ILFD with VCO for Robotics Transmitter

This article presents phase locked loop (PLL) using frequency expansion technique. The oscillator uses a cross-coupled nMOSFET pair in shunt with the LC-resonator. The wide locking range divide-by-2 RLC injection-locked frequency divider (ILFD) is based on a cross-coupled oscillator. The RLC resonator is used to extend the locking range so that dual-band locking ranges can be merged in one locking range at both low and high injection powers. By utilizing pulse interpolation, the proposed architecture is capable of suppressing high-order harmonics of the reference spur as well as fundamental spur. Varactors in series with inductors are used to tune the oscillator frequency. In robotics implementation, a four-stage pulse interpolator achieves 6-dB additional spur suppression.