Table of Contents
Phase-locked loops are typically used to provide local oscillators in radio receivers and transmitters, for clock-signal distribution and noise reduction, and as the clock source for high-speed A/D and D/A converters. As PLL noise decreases, the impact of power supply noise increases, and can even limit noise performance in some cases. This article considers basic PLLs and the power-management requirements for each PLL building block.
Digital potentiometers provide a convenient way to adjust the output of sensors, power supplies, or other devices that require calibration. Digital setting avoids problems associated with mechanical pots, such as physical size, mechanical wear out, wiper contamination, resistance drift, and sensitivity to environmental effects—and eliminates layout inflexibility resulting from the need for access.
Traditional IF and RF transceivers use 50-Ω single-ended interfaces, with interconnected circuits all seeing matching input and output impedances. In modern transceiver designs, differential interfaces provide better performance, but their implementation requires designers to confront impedance matching, common-mode voltage matching, and difficult gain calculations. This article offers some assistance.