Posted 2020/2/26
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.
Noise generated from the bias voltage source is mixed into the sensor output signal. The output
signal and noise are measured by the 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. On the other hand, the signal can be clearly observed by using our low noise DC power supply “LP5394” (Figure 2, left). Thus, even with the same device, the quality of the 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 signals.
Figure 2: Differences of photodiode output signals and noise characteristics depending on bias-voltage source
Related keywords : Low Noise DC Voltage Source
