Analysis of LDO and Decoupling Capacitor Effects on Power Supply Noise Reduction in High-Speed TX

초록

This paper presents an analysis of power-supply noise reduction effects using an analog low-dropout regulator (ALDO) and a decoupling capacitor (Cdc). To evaluate effectiveness, conventional high-speed transmitters are used as devices under test, and the channel is modeled as a 5-cm printed-circuit-board trace. Performance is compared under three conditions: (1) without either Cdc or ALDO, (2) with only Cdc, and (3) with both Cdc and ALDO. Using both components yields a 59.7% reduction in power supply ripple and a 53% reduction in high-level voltage distortion. Moreover, it achieves the most improved eye height and eye in the simulation results.