Oscillator circuits and methods that change frequency in inverse proportion to power source voltage

An oscillator comprising:

• a comparison voltage generating circuit, which is driven by a power source voltage, and generates comparison voltages that change in response to clock signals which have a frequency that varies in inverse proportion to the power source voltage, and a first reference voltage;
• a comparing circuit, which compares levels of the comparison voltages to a second reference voltage and outputs logic signals having logic levels as a result of the comparison;
• a clock switching circuit, which outputs the clock signals which have a frequency that varies in inverse proportion to the power source voltage, in response to the logic signals;
• wherein the level of the second reference voltage is identical to the level of the first reference voltage, to define a single reference voltage;
• and
• a reference voltage generating circuit that generates the single reference voltage in response to a control signal, wherein the reference voltage generating circuit comprises:
• a constant current generating circuit, which generates a constant current in response to the control signal;
• and
• a current mirror circuit, which generates a reference current proportional to the constant current in response to the control signal and outputs the single reference voltage, which is determined by the reference current.

A method of generating an oscillating signal comprising:

• generating comparison voltages that change in response to clock signals which have a frequency that varies in inverse proportion to a power source voltage and a first reference voltage;
• comparing levels of the comparison voltages to a second reference voltage to provide logic signals having predetermined levels as a results of the comparison;
• and
• generating the clock signals which have a frequency that varies in inverse proportion to a power source voltage, in response to the logic signals;
• wherein the level of the second reference voltage is identical to the level of the first reference voltage, to define a single reference voltage;
• the method further comprising generating the single reference voltage in response to a control signal, wherein generating the single reference voltage in response to a control signal comprises:
• generating a constant current in response to the control signal;
• and
• generating a reference current proportional to the constant current in response to the control signal, to provide the single reference voltage, which is determined by the reference current.

A method of generating an oscillating signal comprising:

• generating comparison voltages that change in response to clock signals which have a frequency that varies in inverse proportion to a power source voltage and a first reference voltage;
• comparing levels of the comparison voltages to a second reference voltage that is different from the first reference voltage, to provide logic signals having predetermined levels as a results of the comparison;
• generating the clock signals which have a frequency that varies in inverse proportion to a power source voltage, in response to the logic signals;
• and
• generating the first reference voltage and the second reference voltage in response to a control signal, wherein generating the first reference voltage and the second reference voltage in response to a control signal comprises:
• generating a constant current in response to the control signal;
• generating a first reference current proportional to the constant current in response to the control signal to provide the first reference voltage, which is determined by the first reference current;
• and
• generating a second reference current proportional to the constant current in response to the control signal to provide the second reference voltage, which is determined by the second reference current.