an embodiment of a circuit includes first and second branches , an amplifier , a compensation circuit , and a bias unit . the first and second branches are respectively operable to generate first and second currents . the amplifier has a first amplifier input node coupled to the first branch , a second amplifier input node coupled to the second branch , an amplifier output node coupled to the first and second branches , and a first compensation node . the compensation unit is operable to provide a first offset - compensation signal to the first compensation node . and the first bias unit is operable to provide first and second bias signals to the first and second input nodes , respectively , such that the amplifier is operable to cause the first current to approximately equal the second current .