Patent ID: 7196649

Claim:
An analog to digital converter, comprising: a plurality of comparators, each comparator for comparing an input electrical signal with a respective, pre-selected reference electrical signal, each comparator comprising a comparator for comparing a voltage of the input electrical signal with a voltage of the respective reference electrical signal, the respective reference electrical signal having a pre-selected voltage; an encoder coupled to the comparators to receive a detection signal from each comparator indicative of a voltage of the input signal; and a plurality of reference circuits, each reference circuit coupled to a respective one of the plurality of comparators to supply the respective reference electrical signal to the respective comparator, each reference circuit comprising an output transistor to provide the reference electrical signal; a current source coupled between an emitter of the output transistor and ground; a reference resistor coupled to a base of the output transistor to set an operation current of the output transistor; a control transistor coupled to the reference resistor in parallel with the output transistor to allow current flow through the reference resistor; and a current mirror coupled in parallel with the reference resistor and control transistor to control the current flowing through the reference resistor.