RF Electronics Chapter 10: Operational Amplifiers Page 352
2022, C. J. Kikkert, James Cook University, ISBN 978-0-6486803-9-0.
manufacturers. The noise of operational amplifiers will rise at low frequency, as shown
in figures 10.15, 10.16, 10.19 and 10.20, and is inversely proportional to frequency at low
frequencies, due to flicker noise or 1/f noise. The corner frequency of that 1/f noise may
be important in a design. For example if a microphone amplifier is required, the noise
performance at <1 kHz is important and the ADA4898 has a better noise performance at
those frequencies than the LMH6629, which has a better noise performance at higher
frequencies.
Figure 10.15. Noise of LMH6629 versus frequency [8]
Figure 10.16. Noise and Distortion of ADA4898 [9]
Since the noise sources in the circuit are un-correlated, the total noise from the amplifier
is obtained by adding the noise powers of those sources.
The amplifier configuration and the value of impedances used significantly affect the
resulting noise performance of an amplifier as shown in the following example.
RF Electronics: Design and Simulation
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