- 1). Choose a regulator chip that is specifically designed for low-noise operation. These are available from several manufacturers, including Linear Technology, National Semiconductor and Analog Devices.
- 2). Add capacitance to the input side of the regulator (between the input voltage and ground). The data sheet for your regulator should provide recommendations regarding the specific value and type of capacitor that will be effective in your circuit. In general, a smaller capacitance value will provide better reduction of high-frequency noise, but larger capacitors are also important to maintain a steady input voltage to the regulator.
- 3). Add capacitance between the regulator's output and ground. When reducing noise with output capacitance, you must follow the guidelines in the data sheet. Most linear regulators require a certain amount of capacitance and series resistance to make the regulator stable. If you use a capacitor that is too small, too large, or the wrong type, the output of the regulator may oscillate.
- 4). Add ferrite beads in series with the regulator's input path or output path. If you are primarily trying to reduce noise that is generated by the regulator, the ferrite bead should be in the output path. If your noise is coming from the unregulated voltage supply, put the ferrite bead in the input path. A ferrite bead is a passive device that acts like a wire for low-frequency signals and like a resistor for high-frequency signals (such as noise).
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