Quick‐response phase‐shifter using digital phase‐locked loops

Abstract

AbstractThree types of new quick‐response phase‐shifters are proposed using digital phase‐locked loops (DPLL). They use a new method of level‐slicing the sawtooth waveform of PLL's VCO. The response time for a phase shift (0° ∼ 360°) is less than one period of the input frequency, and is faster than that of conventional ones. Moreover, we group these phase shifters into three classes according to the step response of the input frequency in the DPLL. The first‐class phase shifter has the simplest structure, where a quick response to the input frequency change is not expected so much and a stress is put on eliminating the noise in the input. Its phase shift error increases due to VCO waveform distortion if its response is improved. The second‐class phase shifter realizes a quicker response at the quantization error level by linearizing the VCO waveform. Finally, using the time‐optimal DPLL with the fastest settling time, the response time of the third‐class phase shifter can be made less than one period of the input frequency regardless of the input frequency change.