LO Generation With a Phase Interpolator Digital-to-Time Converter

This paper shows the generation of a local oscillator (LO) signal for cellular transceivers by means of a phase-locked loop and a phase interpolator (PI) digital-to-time converter (DTC). The PI-DTC allows arbitrary frequency shifts over a wide range. We derive a closed-form description of the spurs in the spectrum of the LO signal caused by quantization and nonlinear effects for the PI-DTC. Furthermore, we show the existence of a new class of spurs generated due to noise processes in the PI. Measurement and simulation results are in good agreement with our closed-form solution.