Importance

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Abstract

A bandgap circuit has a pair of NPN bipolar devices that are connected to (i) generate a base-to-emitter voltage difference that is applied across an output-stage resistor and (ii) function as input devices for an amplifier stage that ensures that sufficient current is driven across the output-stage resistor to maintain a desired voltage difference. The desired voltage difference, which has a positive temperature coefficient, is combined with a base-to-emitter voltage of another NPN bipolar device having a negative temperature coefficient to provide a bandgap voltage that is substantially impervious to variations in operating temperature, voltage, and process corners. By using the same two bipolar devices to provide two different functions, there is no need for a separate CMOS-based opamp, which reduces the sources of process mismatch that can adversely affect the bandgap voltage compared to conventional bandgap circuits having bipolar devices and a separate CMOS-based opamp.

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First Claim