1. A capacitance measurement circuit, comprising: a variable current source coupled to drive a selectable current through a circuit node; a switch coupled to the circuit node to switch the selectable current into a device under test (“DUT”) capacitor; and a comparator including first and second input ports, the comparator coupled to compare a first voltage to be received on the first input port against a reference voltage to be received on the second input port, wherein the first voltage is related to the selectable current driven through the circuit node, a switching frequency at which the switch is switched, and a capacitance of the DUT capacitor, wherein the switch is coupled between the first input port of the comparator and the DUT capacitor.