A Contribution to the Discrete Z-Domain Analysis of ADPLL

Abstract

In this paper, a new z-domain model for all-digital phase-locked loop (ADPLL) whose output frequency is inversely proportional to the control word of digital controlled oscillator (DCO) is proposed. With this new z-domain model, bandwidth and phase margin can still be acquired for these ADPLLs. Finally, a cycle-domain simulator is written to verify the correctness of z-domain model and the results are in good agreement within only 0.3-db measurement error bars.