Patent ID: 7279880
Filing Date: 2007-10-09
Classification: G05F

Abstract:
1. A temperature independent low voltage reference circuit comprising: a first transistor with a threshold voltage Vth having a negative temperature coefficient; a diode having a forward voltage drop with a negative temperature coefficient coupled with its anode connected to the drain of the first transistor and its cathode connected to the gate of the first transistor; a power supply terminal; a first resistor coupled between the power supply terminal and the drain of the first transistor; a low voltage supply terminal connected to the source of the first transistor; a second resistor coupled between the gate of the first transistor and the low voltage supply terminal; the drain of the first transistor providing a voltage with a negative temperature coefficient equal to the sum of the forward voltage drop across the diode and the threshold voltage of the first transistor; and a circuit providing a voltage with a positive temperature coefficient coupled between the drain of the first transistor and the low voltage supply terminal and having an output terminal; wherein, said positive temperature coefficient balances said negative temperature coefficient so that the voltage at said output has a temperature coefficient of zero.