1. An operational amplifier capable of self-biasing a first input for use over a broad range of input sources and output load impedances, comprising: a first stage having the first input and a first output, the first output fed back to the first input; a second stage having a second input and a second output, the second input coupled to the first output of the first stage; a third stage having a third input and a third output, the third input coupled to the second output of the second stage, the third output fed back to the third input, the third output negatively fed back to the first input via a feedback resistor, the third output configured to be coupled to an output load via a resistor; a feedback current source connected to the first input; and a configurable voltage source coupled to the first input and to the third output.