An apparatus includes first and second input transistors receiving respective first and second input signals, and a feedback circuit coupled to the first and second input transistors. The first and second input transistors provide first and second nodes with first and second currents according to values of the first and second input signals, respectively, when the feedback circuit is turned on. The first and second input transistors produce a reset value on the nodes when the feedback circuit is turned off. A method includes resetting, using first and second input transistors, respectively, values of first and second nodes to a reset value, providing first and second currents to the nodes using the first and second input transistors according to values of first and second input signals, and determining the values of the nodes according to the values of the first and second input signals.