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 Lecture for Measurement

Posted 2020/2/26

DC-power-supply (AC-DC power supply)

Circuit method and features of DC power supply

3. Noise performance difference by circuit method

Figure 3 and 4 show the noise performance difference between two types: switching and linear regulator. In small signal measurement, noise performance an important factor.

The switching power supply has a lot of large noise at switching frequency and its harmonics (Figure 3). And it has also large humming noise (50 or 60 Hz and its harmonics).

Linear regulator type power supply noise is lower than switching power supply one. However, humming noise may exist due to superimposing in magnetic noise from the power transformer and common-mode coupled from commercial power supply (Figure 4).

Moreover, the disturbance noise may mix in output voltage at both type (Figures 3 and 4). This noise is due to poor shielding of the instrument or humming noise superimposed from the commercial power input.


Figure 3: Noise characteristics of general switching-type power supply


Figure 4: Noise characteristics of general linear regulator type power supply


Related Product

Low Noise DC Voltage Source LP6016-01/P

Bias-voltage and control-voltage source for sensors and devices.

  •  Low noise: 10 µV/√Hz (Bandwidth: 10 Hz to 20 MHz)
  •  High stability: ±10 ppm/°C
  •  Setting accuracy: ±(0.03%+250µ V)
  •  Output voltage: 0 to +16.1 V (LP6016-01)
         0 to +16.1 V x 2ch (LP6016-01P)
  •  Output current: 100 mA
  •  External control interface: USB, RS-232, LAN



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