Transistor base current compensation circuitry

摘要

The accuracy of a bandgap type reference voltage generator which contains bipolar load elements is increased by the use of current compensation circuitry which includes a dummy load element which is the electrical equivalent of the load elements of the generator, an operational amplifier and a current mirror. The operational amplifier and the current mirror act to cause the same potential level (voltage) to be applied to the dummy load element as is applied to the load elements of the generator. A master leg of the current mirror generates a first output current which is identical to the current drawn by the load elements of the generator and provides the current to the dummy load element. A slave leg of the current mirror generates a second output current which is identical to the first output current and which is coupled to the load elements of the generator. Thus current used to drive the load elements of the generator is supplied by the compensation circuitry. This improves the accuracy of the output voltage generated by the reference voltage generator.