An apparatus includes a current-to-voltage converter configured to convert first and second currents into first and second input voltages and provide the first and second input voltages to first and second nodes, respectively, and a current difference determination circuit configured to determine a difference between the first and second currents based on a difference between the first and second input voltages. A method includes converting first and second currents into first and second input voltages to output the first and second input voltages to first and second nodes, respectively, and determining a difference between the first and second currents based on a difference between the first and second input voltages.