8.2.3 Floating Single-Ended Input Line Receiver for Ground Loop Noise Reduction

Ground loops commonly form in audio systems where the equipment is interconnected with coaxial cables, which introduces significant common-mode noise. If the sheath of the coaxial cable is connected to the equipment chassis and safety ground, a ground loop forms, which includes the main electrical wiring and the audio signal path. The INA165x can break these ground loops by floating the sheath of the coaxial cable through resistors (R3 and R4 in Figure 59) so ground noise appears at the inputs of the INA165x as a common-mode signal. Capacitors C8 and C9 provide a high-frequency pathway to ground for radio frequency interference (RFI). A transient voltage suppressor (TVS) connected between the coaxial sheath and the chassis ground is shown in Figure 59. This TVS protects the inputs of the INA165x in the event of an electrostatic discharge to the signal input.

Figure 59. Ground Loop Isolation in Single-Ended Systems