Patent ID: 9537384
Date: 2017-01-03
CPC Classifications: H02M

Claim:
1. A power supply noise reduction circuit that reduces noise included in a constant voltage output that is output from a power supply to a load, the power supply noise reduction circuit comprising: a first resistor that is inserted into a power supply line extending from the power supply to the load; a low-pass filter that is connected to a load terminal of the first resistor and outputs a first voltage that is obtained by reducing the noise from the constant voltage output, the low-pass filter including a second resistor and a capacitor that are connected in series and also including a bypass line for bypassing the second resistor; and a unity gain amplifier that drives the first voltage output from the low-pass filter and outputs the driven first voltage to the load terminal of the first resistor, wherein the low-pass filter is configured to connect the bypass line and bypass the second resistor through a low-pass filter switching unit before the power supply is turned on, wherein the capacitor is charged by turning on the power supply after the bypass line is switched to bypass the second resistor, and wherein after the power supply is turned on and the capacitor is charged the low-pass filter is configured to switch the bypass line to un-bypass the second resistor.