Driving the future of technology : Original solution in measurement and control

 Lecture for measurement

2020/2/26 posted

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

Examples of improved measurement and evaluation by using a low-noise DC power supply

SNR improvement of photodiode by using low noise DC voltage source.

1. Improvement of S / N ratio of photodiode output

Devices such as low noise and high sensitivity amplifiers and sensors are used in the applications that require small signal measurements and high precision signal detections. However, good performance by these devices alone will not provide the best results. This is because the device performance may be affected depending on the quality of the power supply.

A general photodiode is used by applying a reverse bias voltage (Vb). The noise of Vb greatly affects the signal output, so it must be supplied using a low-noise power supply.
Measured how much the noise of bias voltage source affects the output with the measurement system shown in Figure 1.

Figure 1: Measurement system

When using a general linear regulator type power supply, the detected signal is buried in noise and is difficult to observe. In other hand, the signal can be clearly observed by using our low noise DC power supply “LP5394” (Figure 2, left). Thus, even with same device, the quality of power supply can make a significant difference to the output signal. Therefore, it is necessary to pay attention to power supply qualities when measuring small signal.

Figure 2: Differences of a photodiode output signals and noise characteristics depending on bias-voltage source

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



Related keywords :  Low Noise DC Voltage Source

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