In mobile phones, for example, a common practice is to

place the DC-DC converter on one corner of the board,

arrange the CMOS digital circuitry around it (since this also

generates noise), and then place sensitive preamplifiers and

IF stages on the diagonally opposing corner. Often, the

sensitive circuitry is shielded with a metal pan and power to

it is post-regulated to reduce conducted noise, using low-

dropout linear regulators.

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