Patent ID: 7705685

Claim:
An ultra-low-voltage oscillator comprising: a bistable having a first input and a second input and an output that oscillates; a first capacitor having a first capacitance value and a first chargeable plate; a second capacitor having a second capacitance value and a second chargeable plate; a first charging transistor, coupled to the first capacitor, for charging the first chargeable plate of the first capacitor in response to the output being in a first state; a first discharge transistor, coupled to the first capacitor, for continuously discharging the first chargeable plate of the first capacitor; a first sub-threshold transistor, having a gate coupled to the first capacitor, for conducting a first sub-threshold current to the first input of the bistable; a second charging transistor, coupled to the second capacitor, for charging the second chargeable plate of the second capacitor in response to the output being in a second state; a second discharge transistor, coupled to the second capacitor, for continuously discharging the second chargeable plate of the second capacitor; and a second sub-threshold transistor, having a gate coupled to the second capacitor, for conducting a second sub-threshold current to the second input of the bistable; wherein a ratio of the first capacitance value to the second capacitance value determines a duty cycle of the output of the ultra-low-voltage oscillator.