Considerations When Measuring Noise
Exercise care when measuring noise on an output device, such as a power supply or SMU. When verifying the specified wideband noise of a device, the effects of ground loops, unnecessarily long probe ground leads, and electrically noisy environments can combine and skew your measurements.
Observe the following recommendations when measuring the noise of a power supply or SMU:
- Connect the probe directly to the terminals of the power supply or SMU. Do not use long leads, loose wires, or unshielded cables.
- Limit the probe ground lead to a few inches at most. Connect this lead directly to the output common/ground terminal of the appropriate channel.
- Limit the bandwidth of the measurement device to the bandwidth of interest. For example, making a 20 MHz noise measurement with a 200 MHz bandwidth instrument, may not yield the specified values.
- To avoid measuring the environment noise instead of the device noise, exercise caution when making measurements in a modern laboratory environment with computers, electronic ballasts, switching power supplies, and so on.