US Patent 7880661 Analog-digital converter and on-die thermal sensor including the same

An on-die thermal sensor includes an integrating analog-digital converter not requiring a negative reference voltage input. The on die thermal sensor includes a band gap unit, an integrating unit and a counting unit. The band gap unit senses a temperature to output a first voltage corresponding to the sensed temperature. The integrating unit integrates a difference between a reference voltage and a comparing voltage to output a second voltage wherein the comparing voltage has a voltage level higher than that of the reference voltage. The counting unit counts clocks of a clock signal input thereto until the second voltage reaches the first voltage, thereby outputting a thermal code corresponding to the voltage level of the first voltage.