The phase-locked loop (PLL) architecture is studied extensively. It is demonstrated that PLLs are optimal structures in terms of minimizing steady-state mean square tracking error (MSE) at high signal-to-noise ratios (SNR). A closely related device, the delay-locked loop (DLL), is useful for estimating the time delay, or phase, of nonsinusoidal signals. Both PLLs and DLLs fall into the general class known as correlation-loop architectures. It is shown that the steady-state mean square tracking error of first-order correlation loops is minimized by varying the locally generated cross correlation function produced by the voltage controlled oscillator. This analysis assists in the design of modified first-order DLLs used for pseudonoise code synchronization in direct sequence spread-spectrum receivers. The optimization is performed for periodic, but otherwise arbitrary, transmitted signals, for systems operating at arbitrary SNR. The optimal reference waveform is produced by passing a replica of the transmitted signal through a linear time-invariant filter

Meeting Name

IEEE Military Communications Conference, 1990. MILCOM '90


Electrical and Computer Engineering

Keywords and Phrases

PLL; SNR; Correlators; Cross Correlation Function; Cross Correlation Waveforms; Delay-Locked Loop; Direct Sequence Spread-Spectrum Receivers; Filtering and Prediction Theory; First Order Correlation Loops; High Signal-To-Noise Ratios; Linear Time-Invariant Filter; Mean Square Tracking Error; Nonsinusoidal Signals; Optimal Reference Waveform; Optimization; Periodic Signals; Phase; Phase-Locked Loop; Phase-Locked Loops; Pseudonoise Code Synchronization; Radio Receivers; Spread Spectrum Communication; Steady State Error; Time Delay; Voltage Controlled Oscillator

Document Type

Article - Conference proceedings

Document Version

Final Version

File Type





© 1990 Institute of Electrical and Electronics Engineers (IEEE), All rights reserved.