Virtual Ground in Single Supply Operation
Generation of a virtual ground is required by single-supply operation. It’s usually required at a voltage equal to Vcc/2. We can use a simple voltage divider produce Vcc/2, but it’s performance deteriorates at low frequency. The values of R1 and R2 are equal, selected with power consumption Vs allowable noise in mind. We can eliminate conducted noise on the voltage rail with a low-pass filter formed by capacitor C1. Some applications are available to omit the buffer op amp.
There are a few circuits in which because one virtual ground is not suitable, a virtual ground has to be introduced with two resistors within the circuit. The resistors should be 100 k or greater, when such a problem arises, values are indicated on the circuit diagram. [Source: Texas Instruments Application Note]