Patent ID: 7863883

Claim:
A low-voltage current reference providing a current being substantially constant with temperature, the low-voltage current reference comprising: a low voltage bandgap, for providing a constant voltage reference; a start circuit coupled to the low voltage bandgap, for starting the low voltage bandgap from a non-start mode and for providing a proportional to absolute temperature (PTAT) current reference; and a current summer coupled to the low voltage bandgap and to the start circuit, for providing a constant current reference according to the constant voltage reference and the PTAT current reference; wherein within the low voltage bandgap, values of at least a first resistor and a first diode connected in series are selected to provide a first internal PTAT current flowing through at least the first resistor and the first diode, the first resistor has one end connected to the first diode and having another end coupled to a first voltage node; and the start circuit comprises: a first operational amplifier (op amp) having a positive input, a negative input coupled to the first voltage node, and an output; a second transistor having a gate coupled to the output of the first op amp, and a source coupled to power; and a circuit, coupled to the second transistor, wherein a second internal PTAT current flows through the circuit.