Bandgap circuit for current and voltage

摘要

A simple bandgap current generator combines a PTAT (proportional to absolute temperature) base-emitter voltage (VBE) measured across two binary junction devices (ΔVBE=VBE1−VBE2) with a current that is varied by an nWell resistor with a positive temperature coefficient to produce a CTAT (complementary to absolute temperature) current instead of PTAT reference current. One of the base-emitter voltages is constrained to be VBE1=VBE(1βT). This reduces the temperature dependency of a reference current generated by the bandgap generator. This reference current may be used to generate a bandgap reference voltage by adding an IR drop to a diode voltage or to a base-emitter voltage. The simple bandgap circuit is significantly smaller in size than a precision bandgap circuit, but still provides a voltage and/or a current reference signal having a good accuracy.

主权项

1. A method for operating a bandgap reference circuit, the method comprising: producing a bias current through a first resistor having a positive temperature coefficient in a first translinear loop such that the bias current has a positive temperature coefficient;
producing a delta base emitter voltage (VBE) between a first bipolar junction transistor (BJT) having a higher VBE and a second BJT having a lower VBE across a second resistor in a second translinear loop, wherein the second resistor has a positive temperature coefficient; using the bias current produced by the first translinear loop to bias the first BJT of the second translinear loop, wherein the positive temperature coefficient of the bias current compensates for the positive temperature coefficient of the second resistor; and producing a temperature compensated reference current through the second resistor responsive to the delta VBE; and wherein the second translinear loop comprises the first and the second BJT as two base connected BJTs coupled to inputs of an amplifier, wherein the second resistor is connected between a first input of the amplifier and an emitter of one of the BJTs.