Input coupling capacitors are not required. A fully differential amplifier with good CMRR, such as the TPA6211A1-Q1 device, allows the inputs to be biased at voltage other than mid-supply. For example, if a DAC has a lower mid-supply voltage than that of the TPA6211A1-Q1 device, the common-mode feedback circuit compensates, and the outputs are still biased at the mid-supply point of the TPA6211A1-Q1 device. The inputs of the TPA6211A1-Q1 device can be biased from 0.5 V to V_DD – 0.8 V. If the inputs are biased outside of that range, input coupling capacitors are required.

A Mid-supply bypass capacitor, C_BYPASS, is not required. The fully differential amplifier does not require a bypass capacitor. Any shift in the mid-supply voltage affects both positive and negative channels equally, thus canceling at the differential output. Removing the bypass capacitor slightly worsens power supply rejection ratio (k_SVR), but a slight decrease of k_SVR can be acceptable when an additional component can be eliminated (see Figure 5-17).

The RF-immunity is improved. A fully differential amplifier cancels the noise from RF disturbances much better than the typical audio amplifier.