Patent ID: 7786707

Claim:
An oscillator circuit comprising: a reference current circuit generating a reference current; a first charging and discharging circuit comprising a first capacitor, a first switching circuit switching the first charging and discharging circuit from an initializing operation initializing a voltage of a terminal of the first capacitor to a power supply voltage and to a discharging operation allowing the reference current to flow from the first capacitor and switching the first charging and discharging circuit from the discharging operation to the initializing operation, and a first detection circuit detecting the voltage of the terminal of the first capacitor and outputting a first clock based on the detection; a second charging and discharging circuit comprising a second capacitor, a second switching circuit switching the second charging and discharging circuit from an initializing operation initializing a voltage of a terminal of the second capacitor to a power supply voltage and to a discharging operation allowing the reference current to flow from the second capacitor and switching the second charging and discharging circuit from the discharging operation to the initializing operation, and a second detection circuit detecting the voltage of the terminal of the second capacitor and outputting a second clock based on the detection; and a control circuit controlling the first and second switching circuits so that the first and second charging and discharging circuits alternately perform corresponding initializing operations and the discharging operations in response to the first and second clocks, wherein the reference current circuit comprises a resistor and a first MOS transistor serially connected between a power supply terminal and a ground terminal, a gate of the first MOS transistor is connected to a drain of the first MOS transistor, the first detection circuit comprises a second MOS transistor serially connected between the power supply terminal and the ground terminal and comprising a gate connected to the terminal of the first capacitor, and the first detection circuit has a threshold voltage equal to a voltage applied between a source of the first MOS transistor and the connected gate and drain of the first MOS transistor.