Mosfet reference voltage circuit

Abstract

A stable temperature-insensitive constant reference voltage circuit is provided which can be implemented in either MOS or bipolar technology. The circuit may be implemented by MOSFET devices on a single chip with another circuit such as an A/D converter to provide a monolithic A/D converter with its own internal reference voltage circuit. The reference voltage circuit consists of a series-connected long channel MOSFET and short channel MOSFET which produce, at their junction, a temperature-independent voltage. A differential circuit containing three MOSFET devices is then provided with one of the devices serving as a current source which carries the current of the other two MOSFET devices which are in parallel. The gates of the two parallel MOSFET devices are connected respectively to the junction between the long channel and short channel device and to the output voltage. Current divides between the two parallel MOSFET devices in such a way as to cause a constant output voltage to be produced regardless of the variations of the supply voltage sources V.sub.dd or V.sub.gg. The various MOSFET devices are formed on the same substrate containing the circuit components being connected to the constant stable voltage reference source.