Oscillation circuit and semiconductor device free from the influence of source voltage, temperature and fluctuations in the inverter threshold voltage

A semiconductor device including an oscillation circuit capable of oscillation by utilizing charging/discharging of a capacitive element, comprising:

• an inverter for inverting a voltage applied to one end of the capacitive element and outputting the inverted voltage;
• a constant voltage source for outputting a constant voltage free from influence of a source voltage and temperature;
• a switching circuit for connecting the other end of the capacitive element to one of the constant voltage source and ground in accordance with the voltage output from the inverter;
• a constant current source for causing a constant current free from the influence of the source voltage and temperature to flow into or out of the one end of the capacitive element in accordance with the voltage output from the inverter, and
• a bias generator circuit for generating a temperature-dependent voltage having temperature dependency identical with that of a resistor and applying the temperature-dependent voltage to the resistor to generate the constant current and thus a bias voltage,
• wherein the bias generator circuit controls current sources included in the constant current source in accordance with the bias voltage, to generate the constant current.

An oscillation circuit capable of oscillation by utilizing charging/discharging of a capacitive element, comprising:

• an inverter for inverting a voltage applied to one end of the capacitive element and outputting the inverted voltage;
• a constant voltage source for outputting a constant voltage free from influence of a source voltage and temperature;
• a switching circuit for connecting the other end of the capacitive element to one of the constant voltage source and ground in accordance with the voltage output from the inverter;
• and
• a constant current source for causing a constant current free from the influence of the source voltage and temperature to flow into or out of the one end of the capacitive element in accordance with the voltage output from the inverter, and
• wherein the switching circuit includes:
• a P-channel transistor having a source connected to the constant voltage source;
• and
• an N-channel transistor having a source connected to the ground, a drain connected to the drain of the P-channel transistor as well as to the other end of the capacitive element, and a gate connected to the gate of the P-channel transistor and input with the voltage output from the inverter.

An oscillation circuit capable of oscillation by utilizing charging/discharging of a capacitive element, comprising:

• an inverter for inverting a voltage applied to one end of the capacitive element and outputting the inverted voltage;
• a constant voltage source for outputting a constant voltage free from influence of a source voltage and temperature;
• a switching circuit for connecting the other end of the capacitive element to one of the constant voltage source and ground in accordance with the voltage output from the inverter;
• and
• a constant current source for causing a constant current free from the influence of the source voltage and temperature to flow into or out of the one end of the capacitive element in accordance with the voltage output from the inverter, and
• wherein the constant current source includes:
• a P-channel transistor having a source connected to a current source for causing the current to flow into the capacitive element;
• and
• an N-channel transistor having a source connected to a current source for causing the current to flow out of the capacitive element, the N-channel transistor having a drain connected to the drain of the P-channel transistor as well as to the one end of the capacitive element, and a gate connected to the gate of the P-channel transistor and input with the voltage output from the inverter.

A semiconductor device including an oscillation circuit capable of oscillation by utilizing charging/discharging of a capacitive element, comprising:

• an inverter for inverting a voltage applied to one end of the capacitive element and outputting the inverted voltage;
• a constant voltage source for outputting a constant voltage free from influence of a source voltage and temperature;
• a switching circuit for connecting the other end of the capacitive element to one of the constant voltage source and ground in accordance with the voltage output from the inverter;
• and
• a constant current source for causing a constant current free from the influence of the source voltage and temperature to flow into or out of the one end of the capacitive element in accordance with the voltage output from the inverter, and
• wherein the switching circuit includes:
• a P-channel transistor having a source connected to the constant voltage source;
• and
• an N-channel transistor having a source connected to the ground, a drain connected to the drain of the P-channel transistor as well as to the other end of the capacitive element, and a gate connected to the gate of the P-channel transistor and input with the voltage output from the inverter.

A semiconductor device including an oscillation circuit capable of oscillation by utilizing charging/discharging of a capacitive element, comprising:

• an inverter for inverting a voltage applied to one end of the capacitive element and outputting the inverted voltage;
• a constant voltage source for outputting a constant voltage free from influence of a source voltage and temperature;
• a switching circuit for connecting the other end of the capacitive element to one of the constant voltage source and ground in accordance with the voltage output from the inverter;
• and
• a constant current source for causing a constant current free from the influence of the source voltage and temperature to flow into or out of the one end of the capacitive element in accordance with the voltage output from the inverter, and
• wherein the constant current source includes:
• a P-channel transistor having a source connected to a current source for causing the current to flow into the capacitive element;
• and
• an N-channel transistor having a source connected to a current source for causing the current to flow out of the capacitive element, the N-channel transistor having a drain connected to the drain of the P-channel transistor as well as to the one end of the capacitive element, and a gate connected to the gate of the P-channel transistor and input with the voltage output from the inverter.