Precision temperature sensor

1. A temperature sensor circuit comprising:

a temperature sensing element operable to provide a temperature voltage that is linearly related to the absolute temperature of the circuit, the temperature sensing element comprising:

a first bi-polar junction transistor and a second bipolar junction transistor connected between a supply voltage and a common ground, wherein the base of first bipolar junction transistor is connected to the base of the second bipolar junction transistor each bipolar junction transistor;

a first resistor connected between an emitter of the first bipolar junction transistor and the common ground; and

a second resistor connected between the common ground and a first node, wherein the temperature voltage is provided to the first node across the second resistor;

a current supply element operable to supply a common current to a collector of the first bipolar junction transistor, the second bipolar junction transistor and the second resistor, respectively;

an early voltage element operable to compensate for variations in voltage;

a base current element operable to provide a steady base current to the bases of the first and second bipolar junction transistors;

a channel modulation element operable to compensate for channel modulation; and

a leakage element operable to compensate for epi-substrate leakage between the circuit and a substrate on which it is formed.

2. The temperature sensor circuit of claim 1 , further comprising a start up circuit operable to ensure that the common current is stable at start up and that is disengaged after a predetermine period of time.

3. The temperature sensor circuit of claim 2 , wherein the current supply element further comprises a frequency compensation element operable to compensate for frequency changes in the current supply element such that the common current remains stable.

4. The temperature sensor circuit of claim 3 , further comprising:

a voltage regulator, connected to the temperature sensor circuit and operable to provide a steady supply voltage to the temperature sensor circuit.

5. The temperature sensor circuit of claim 4 , wherein the current supply element further comprises:

a positive feedback gain loop operable to provide the common current to the first bipolar junction transistor; and

a negative feedback gain loop operable to provide the common current to the second bipolar junction transistor.

6. The temperature sensor circuit of claim 5 , wherein the leakage elemement further comprises:

a first epi diode connected across the second bipolar junction transistor; and

a second epi diode connected across the second resistor, such that the additional epi-substrate junctions provided in the first and second epi diodes reduces the affect of epi-substrate leakage.

7. The temperature sensor circuit of claim 6 , wherein the temperature sensor circuit is implemented in an integrated circuit.