Relaxation oscillator and method for providing an output frequency. For example, the relaxation oscillator includes a reference generator, a capacitor, a first comparator, a second comparator, a latch, and a temperature compensation circuit. The reference generator is configured to generate a first bias current, a first bias voltage and a second bias voltage. The capacitor is configured to be charged by a charging current to generate a charged voltage, and the charging current is generated based on at least the first bias current. The first comparator is configured to compare the charged voltage and the first bias voltage to generate a first comparison result, and the second comparator is configured to compare the charged voltage and the second bias voltage to generate a second comparison result. The latch is configured to generate a clock signal based on at least the first comparison result and the second comparison result.