techniques are provided for producing two output voltages that are substantially symmetric about a middle voltage , based on a digital data value stored in a register . a first output voltage is produced based on the digital data value stored in the register . additionally , the digital data value stored in the register is converted to a second digital data value , which is used to produce a second output voltage that is substantially symmetric about vcom with the first output voltage . alternatively , the digital data value stored in the register is provided to two different dacs that have their pair of reference voltages swapped , which will result in the outputs of the dacs being substantially symmetric about vcom .