Analysis and Measurement of Intrinsic Noise in Op Amp Circuits Part VI: Noise Measurement Examples by Art Kay, Senior Applications Engineer, Texas Instruments Incorporated
In Part IV we introduced the different types of equipment used for measuring noise. Now in Part VI, we discuss specifications and modes of operation pertinent to noise measurement. Here we will show real-world examples of how the equipment is used to measure the circuits described in Parts III and IV.
Shielding
When measuring intrinsic noise it is important to eliminate sources of extrinsic noise. Common sources of extrinsic noise are power line pick-up (ie 50 Hz or 60 Hz), monitor noise, switching power supply noise and wireless communication noise. Normally elimination is by keeping the circuit under test in a shielded enclosure, usually made of copper, iron or aluminum; it is important that the shield be connected to system ground.
