Junction field effect voltage reference

Claim 1

A JFET voltage reference which provides a positive output voltage, comprising: a pair of JFETs having source, drain and gate terminals, different channel doping densities which result in unequal pinchoff voltages, and equal channel width-to-length ratios, each JFET characterized by a source-drain current path between its respective source and drain terminals, an operational amplifier having inverting and noninverting inputs and an output, and a pair of equal current current sources, the source-drain current paths of said JFETs connected to opposite respective ones of said operational amplifier inputs and also to receive equal currents from said current sources and to establish respective current flow paths between said current sources and a ground reference through respective ones of said JFET source-drain current paths, said current source currents being sufficient to maintain said JFETs in saturation, and the gates of said JFETs connected across a resistor, said resistor being part of a resistance circuit that is connected to the operational amplifier output to reproduce the difference in pinchoff voltages between said JFETs across said resistor and to establish a voltage reference output as a function of the voltage across said resistor.