An adder circuit can be fabricated within an integrated circuit (IC) and can be configured to draw a sum output node to a voltage proportional to a sum of received N-bit binary numbers. The adder circuit includes sets of N inputs that receive N-bit binary numbers, each set of N inputs indexed by an integer bit number “n.” The adder circuit includes sets of scaled capacitors, each capacitor connected to an nth input of the corresponding set of N inputs and to the sum output node. Each scaled capacitor has a capacitance equal to 2(n)*a unit capacitance (CUNIT). The adder circuit includes a reference capacitor connected to ground and the sum output node, and a reset circuit configured to draw, in response to a received RESET signal, the sum output node to ground.