A circuit for generating a reference voltage which is independent of temperature and supply voltage includes a bandgap stage supplying the reference voltage, a first circuit receiving the supply voltage and generating an output voltage being substantially free of variations in the supply voltage, and a second circuit connected to the first circuit and driven by the output voltage, the second circuit being connected to the bandgap stage for supplying a current to the bandgap stage having a characteristic for compensating and eliminating temperature dependencies in the bandgap stage.

Bandgap circuit for generating a temperature-independent reference voltage, including a diode-resistance path at which a temperature-independent reference voltage corresponding to the energy gap of semiconductor material of components used in the circuit is available, the diode-resistance path including a diode and a series circuit of at least two resistors being connected in parallel with the diode, a temperature-independent reference voltage which is independent of the energy gap of the semiconductor material being available at one of the resistors.

An all NPN bandgap voltage reference is provided that includes a Widlar type temperature coefficient compensation circuit. A pair of NPN differentially connected transistors maintain a constant current in the Widlar circuit over variations in power supply voltage V.sub.EE while causing an increase in current in the Widlar circuit as temperature increases for maintaining a constant output voltage.

A bandgap voltage reference of a unique design is disclosed. The reference utilizes a pair of transistors operating at different current densities to provide a current component through a resistor at the .DELTA.V.sub.BE of the two transistors. A second current component through the resistor is provided through another resistor connected to the common emitter connection of another pair of transistors, the collectors of the last named pair of transistors each being connected to one input of a operational amplifier, the output of which is the output of the circuit. In operation, the base of one of the last named pair of transistors is connected to a resistor divider on the circuit output and held at the bandgap voltage, the base of the other of the last named pair of transistors also being held at the bandgap voltage by being connected to a resistor divider between the collector of one of the two transistors operating at different current densities and the emitter of a fifth transistor, the base of the fifth transistor being connected to the resistor divider on the circuit output at a point corresponding to a voltage of two bandgap voltages. By proper selection of transistor size ratios and resistor ratios, a high degree of symmetry can be achieved.

A bandgap-based reference voltage generator circuit with an increased output reference voltage and a reduced temperature coefficient uses a curvature correction bias voltage to significantly reduce the degree of variation of the bandgap-based reference voltage over temperature. A current having a negative temperature coefficient is conducted by a resistor having a positive temperature coefficient. The resultant voltage across the resistor has an arcuate voltage-versus-temperature characteristic with a direction of incurvature that is substantially opposite the direction of incurvature of the corresponding arcuate voltage-versus-temperature characteristic of the voltage generated by a conventional bandgap reference voltage generator circuit. These voltages are summed together to produce a bandgap-based reference voltage which is greater in magnitude than a conventional bandgap reference voltage and has a significantly reduced temperature coefficient.