A relaxation oscillator for generating a low temperature coefficient (LTC) clock signal includes a reference voltage generator and an oscillator. The reference voltage generator generates an LTC current and a bandgap reference voltage. The reference voltage generator includes positive temperature coefficient (PTC) resistors to compensate for the effects of temperature variations. The oscillator receives the LTC current and the bandgap reference voltage, and generates a clock signal. In another embodiment, the reference voltage generator generates a charge current that varies with temperature. The oscillator receives the charge current and generates first and second output signals. Set and reset comparators include PTC resistors that determine the gains of the set and reset comparators. The PTC resistors compensate for variation in the first and second output signals due to the temperature variations by varying the gains of the set and reset comparators.