Constant current driven oscillating circuit
There is provided a constant current driven oscillating circuit including: an oscillator with first and second ends; a first field effect transistor that turns ON when a signal of a lower level than a first threshold voltage is input to a first gate terminal, and outputs, from a second terminal, current that has been input from a first terminal; a second field effect transistor turning ON when a signal output from the oscillator and is at a higher level than a second threshold voltage is input to a second gate terminal connected to the second end of the oscillator, and outputs, from a fourth terminal, current that has been input from a third terminal connected to the second terminal and to the first end of the oscillator; and an adjusting section that adjusts the first threshold voltage according to the level of the signal output from the oscillator.
1. 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.
2. The constant current driven oscillating circuit of claim 1 , further comprising:
a return resistor having a first end connected to the gate terminal of the second field effect transistor, and a second end connected to the third terminal of the second field effect transistor.
3. The constant current driven oscillating circuit of claim 1 , wherein the first field effect transistor is a P-channel field effect transistor, and the second field effect transistor is an N-channel field effect transistor.
4. The constant current driven oscillating circuit of claim 1 , the oscillator comprising a liquid crystal oscillator element, a first condenser connected to a first electrode of the liquid crystal oscillator element, and a second condenser connected to a second electrode of the liquid crystal oscillator element.