Switched capacitor temperature independent bandgap reference
 A temperature stable bandgap voltage reference source utilizing two substrate bipolar transistors biased at different emitter current densities is provided. Switched capacitors are used to input the V.sub.be and the .DELTA.V.sub.be of the transistors (NTC and PTC voltages, respectively) into an amplifier to provide a reference voltage proportional to the weighted sum of the PTC and NTC voltages. Proper selection of the ratio of the switched capacitors renders the reference voltage substantially independent of temperature. In a modified form of the reference, the reference amplifier is implemented by an auto-zeroed operational amplifier which uses switched capacitor techniques and an integrated capacitor to achieve the auto-zeroing function. 
Motorola, Inc.
G
G05F
inventional
Roger A. Richard W.
Whatley Ulmer