低噪声音频线路设计AMPLIFIER AND COMPARATOR CIRCUITS AUDIO CIRCUITS FILTER CIRCUITS (ANALOG) POWER-SUPPLY CIRCUITS Jul 01, 2001 Low Noise Audio Power Supply Circuit Audio application note describes a simple, compact scheme that provides a low noise, low ripple power source for use in audio amplifiers, microphones, headphone amplifiers, CODECs and other audio circuits. The circuit shown in the figure below reduces noise and ripple voltage by 40dB over the 100Hz to 20kHz audio range. It provides a clean source of 5V power for driving audio circuits in portable applications such as cellular phones and multimedia notebook computers. Most linear regulators reject noise only up to 1000Hz or so, and the bulk of a low-frequency passive filter is unwelcome in portable applications. This compact circuit actively co……