Patent ID: 7581881

Claim:
A temperature sensor, comprising: a first bias unit having a variable amount of an internal current that varies in response to temperature and generating first and second bias signals; a second bias unit having a fixed amount of an internal current and generating third and fourth bias signals; a first ring oscillator generating a first clock signal in response to the first and second bias signals; a second ring oscillator generating a second clock signal in response to the third and fourth bias signals; a one-shot pulse generator latching one pulse of the first clock signal and generating a one-shot pulse; and a temperature code generator counting a width of the one-shot pulse as a pulse of the second clock signal and generating a temperature code, wherein the first bias unit includes: a first PMOS transistor having a source connected to a power voltage, and having an interconnected gate and drain; a resistor connected between the drain of the first PMOS transistor and a ground voltage; a second PMOS transistor having a source connected to the power voltage and having a gate connected to the gate of the first PMOS transistor to generate the first bias signal; and an NMOS transistor having a gate and drain connected to a drain of the second PMOS transistor to generate the second bias signal, and having a source connected to the ground voltage.