An oscillator includes an oscillating circuit having an input and an output configured to oscillate between a first state and a second state. The oscillating circuit includes a resistor-capacitor circuit configured to bias the oscillating circuit input towards a target voltage. The oscillating circuit is configured to transition the oscillating circuit output from the first state to the second state in response to the oscillating circuit input reaching a threshold voltage before it reaches the target voltage. Another oscillator includes an oscillating circuit having an input and an output configured to oscillate between the first state and the second state. The oscillating circuit is configured to transition the oscillating circuit output from the first state to the second state in response to the oscillating circuit input reaching a threshold voltage. A starting circuit is configured to set the oscillating circuit input to the threshold voltage to start the oscillating circuit.