CTAT generator using parasitic PNP device in deep sub-micron CMOS process

摘要

A control circuit generates a current that remains substantially constant over temperature using a bandgap reference for providing a PTAT current. A first current mirror generates a current proportional to the PTAT current. A novel complementary to absolute temperature (CTAT) current source provides a CTAT current void of bipolar transistor base current, regardless of whether it is implemented in a CMOS digital process or not. It includes a first bias current source that connects to a first resistive circuit and a first subcircuit portion. The first subcircuit portion, including a first bipolar transistor, generates a current proportional to the base emitter voltage of the first bipolar transistor and the base current of the first bipolar transistor. A second bias current source connects to a second resistive circuit and a second subcircuit portion. The second subcircuit portion, including a second bipolar transistor, generates a current proportional to the base current of the second bipolar transistor. A second current mirror connects between the first subcircuit portion and the second subcircuit portion to subtract the base current of the first bipolar transistor and, thus, provide a CTAT current proportional to the first and second resistive circuits. A third current mirror connects between the second current mirror and the first current mirror such that the PTAT current and the CTAT current are summed together to provide current that remains substantially constant over temperature.