Patent ID: 8067993

Claim:
A constant current driven oscillating circuit comprising: an oscillator with a first end and a second end; a first field effect transistor having a first terminal, a second terminal and a first gate terminal, that turns ON when a signal of a lower level than a first threshold voltage is input to the first gate terminal, and outputs, from the second terminal, current that has been input from the first terminal; a second field effect transistor having a third terminal, a fourth terminal and a second gate terminal, the third terminal being connected to the second terminal and to the first end of the oscillator, and the second gate terminal being connected to the second end of the oscillator, the second field effect transistor turning ON when a signal that is output from the oscillator and is at a higher level than the second threshold voltage is input to the second gate terminal, and outputs, from the fourth terminal, current that has been input from the third terminal; and an adjusting section that, when the first field effect transistor turns ON, adjusts the first threshold voltage according to the level of the signal output from the oscillator, the adjusting section comprising: a resistor, the first end of the resistor being connected to a power source and the second end of the resistor being connected to a back gate terminal of the first field effect transistor; and a condenser, a first electrode of the condenser being connected to the second end of the resistor, and a second electrode of the condenser being connected to the gate terminal of the second field effect transistor.