Abstract: A low cost, low power and low noise temperature sensor circuit is disclosed. A control circuit asserts a start signal and a stop signal, causes a pulse generating circuit to generate a finite number of pulses, whose pulse frequency varies with temperature. A counter counts the finite number of pulses and outputs the count which can be used to represents the temperature. Further, the pulse generating circuit includes a delay circuit, a pulse width controlling circuit, and a synchronizer with asynchronous clear.