The calculation of noise in operational amplifier circuits is discussed.
Noise calculations in op amp circuits are one of the most confused calculations that an analog engineer must perform.
One cannot just look at noise specifications; the total op amp circuit including resistors and operating frequency range must be included in calculations for circuit noise. A “low” noise amplifier in one circuit will become a “high” noise amplifier in another circuit.
As part of this design note, an IBM-PC2 or compatible computer program, NOISE, has been written to perform the noise calculations. This program allows the user to ...