Study on Low-jitter and Low-power PLL Architectures for Mobile Audio Systems

Abstract

This paper compares four phase-locked loops (PLLs) for mobile audio applications. We compare and analyze PLL structures and discuss the optimized PLL structure in the audio band frequency. A charge-pump-based integer-N PLL (NPLL) is employed as a reference. To improve the jitter performances, multiplying delay-locked loop (MDLL), sub-sampling PLL (SSPLL), and reference-sampling PLL (RSPLL) are employed and analyzed. The frequency range of the PLLs is from 8 MHz to 71.5 MHz. These PLL chips are fabricated using a Samsung 0.13-μm CMOS process. The resulting figures-of-merit for the NPLL, MDLL, SSPLL, and RSPLL are −204.3, −211.07, −220.29, and −213.32 dB, respectively, at 24.576 MHz. The total power consumption from a 1.5-V supply voltage is 1.82, 1.35, 1.43, and 1.64 mW, respectively.