For best operational performance of the device, use good PCB layout practices, including:
- Noise can propagate into analog circuitry through the power pins of the circuit as a whole, as well as the operational amplifier. Bypass capacitors are used to reduce the coupled noise by providing low impedance power sources local to the analog circuitry.
- Connect low-ESR, 0.1-μF ceramic bypass capacitors between each supply pin and ground, placed as close as possible to the device. A single bypass capacitor from V+ to ground is applicable for single supply applications.
- Separate grounding for analog and digital
portions of circuitry is one of the simplest and most-effective methods of noise
suppression. One or more layers on multilayer PCBs are usually devoted to ground planes. A
ground plane helps distribute heat and reduces EMI noise pickup. Make sure to physically
separate digital and analog grounds, paying attention to the flow of the ground current.
For more detailed information, see Circuit Board Layout
Techniques.
- To reduce parasitic coupling, run the input traces as far away as possible from the supply or output traces. If keeping the traces separate is not possible, then cross the sensitive trace perpendicular, as opposed to in parallel with the noisy trace.
- Keep the length of input traces as short as possible. Always remember that the input traces are the most sensitive part of the circuit.