Oscillation circuit capable of having stable oscillation in wide temperature range
An oscillation circuit includes a constant current source, a current mirror circuit configured to receive a constant input current from the constant current source and to output a current proportional to the constant input current, a first inverter configured to be driven with a quartz resonator to oscillate, an operational amplifier configured to supply power to the first inverter with a voltage equal to an input voltage of the operational amplifier and a second inverter having a power supply terminal connected to the current mirror circuit and to the operational amplifier and configure to generate the input voltage for the operational amplifier.
1. An oscillation circuit comprising;
a constant current source;
a current mirror circuit configured to receive a constant input current from the constant current source and to output a current proportional to the constant input current;
a first inverter configured to be driven with a quartz resonator to oscillate;
an operational amplifier configured to supply power to the first inverter with a voltage equal to an input voltage of the operational amplifier; and
a second inverter having a power supply terminal connected to the current mirror circuit and to the operational amplifier and configure to generate the input voltage for the operational amplifier.
2. The oscillation circuit according to claim 1 , wherein the second inverter has an input and an output terminal connected to each other.
3. The oscillation circuit according to claim 1 , wherein the voltage of the power supplied from the operational amplifier to the first inverter changes in accordance with temperature.
4. The oscillation circuit according to claim 1 , wherein:
the second inverter comprises an N-channel MOSFET transistor and a P-channel MOSFET transistor; and
the second inverter has electrical characteristics and temperature dependence substantially equivalent to electrical characteristics and temperature dependence of the first inverter.