Chaotic behavior of 741 opamps subjected to EMI conveyed to power supply rails

In this paper the experimental chaotic behavior of the well known 741 operational amplifier is presented when electromagnetic interference is conveyed to its power supply pins. Such a complex dynamic behavior occurs if the interfering signal is in the 5 MHz-28 MHz range with amplitudes greater than about 100 mV. These frequencies are out of the standard operating conditions, but they easily occur in real applications as a result of interference. The chaotic behavior was measured on 741 amplifiers of three different manufacturers and it was also verified by simulation of an equivalent circuit described in the literature. The strong similarities between simulation and measurements argue that the chaotic behavior is a property of the amplifier circuit architecture and it is not an effect of the package or due to the experimental setup.