Patent ID: 8278909

Claim:
An electrometer, comprising: an amplifier having an inverting input, a non-inverting input, and an output; first and second resistive elements each having a first end and a second end, the first ends of the first and second resistive elements electrically coupled to the inverting input of the amplifier and the second end of the first resistive element electrically coupled to the output of the amplifier; a buffer having a high-impedance input and an output, the second end of the second resistive element electrically coupled to the input of the buffer; and at least one diode electrically coupling the output of the amplifier to the second end of the second resistive element, wherein the buffer is a second amplifier having an inverting input, a non-inverting input, and an output, the output of the second amplifier being electrically coupled to the inverting input of the second amplifier, the non-inverting input of the second amplifier being the input of the buffer and the output of the second amplifier being the output of the buffer.