Patent ID: 8542052

Claim:
An electrical circuit for emulating a capacitance, comprising; a physical capacitor which is charged by charge flow from an input of the electrical circuit; an amplifier for amplifying the voltage at the input of the electrical circuit such that the physical capacitor is charged with a larger change in voltage than a change in voltage at the input; and a reset system for resetting a state of charge of the physical capacitor without drawing charge from the input of the electrical circuit; wherein the amplifier and the physical capacitor form an amplifying integrator circuit, wherein the physical capacitor is in a first feedback path between an output of the amplifier and a first input of the amplifier with the input of the electrical circuit provided to the first input of the amplifier, wherein the electrical circuit further comprises a gain element in a second feedback path between the output of the amplifier and a second input of the amplifier, and wherein the reset system comprises: a control circuit for controlling the second feedback path in dependence on a voltage at the input of the electrical circuit, wherein the control circuit comprises a circuit for controlling one of a current and a voltage provided to the gain element; an up/down counter that counts up when the voltage at the output of the amplifier reaches a first level compared to the input and counts down when the voltage at the output of the amplifier reaches a second level compared to the input; and a D/A converter that converts the output of the up/down counter to an analogue signal, wherein the analogue signal is applied to an input of the gain element.