Patent ID: 7046017

Claim:
An electrical circuit for measuring capacitance, comprising: a signal generating mechanism for generating a signal having a predefined frequency and predefined low and high voltage levels; a switching mechanism for coupling an input to one of two outputs; a first amplifier with a gain, wherein an input of the first amplifier is coupled to a first of the outputs of the switching mechanism and an output of the first amplifier is coupled to an output node in the circuit; a second amplifier with a gain, wherein an input of the second amplifier is coupled to a second of the outputs of the switching mechanism and an output of the second amplifier is coupled to the output node; and a load having at least two terminals and an unknown capacitance between the terminals, wherein one of the terminals is coupled to the signal generating mechanism and another of the terminals is coupled to the input of the switching mechanism, wherein the switching mechanism is selectively substantially coupled to the first amplifier and the second amplifier in order to full-wave rectify current flowing between the two terminals in the load.