Oscillator circuit having oscillation frequency independent from the supply voltage value

Method for generating an oscillating electric signal through an electric circuit comprising a capacitor, a charge circuitry and a control circuitry and in which said charge circuitry possesses at least first and second operational conditions and said first operational condition corresponds to the injection in said capacitor of a current having a first value and said second operational condition corresponds to the extraction from said capacitor of a current having a second value, the method comprising the step of:

• causing said control circuitry to activate alternately said first or said second operational condition depending on whether the voltage across said capacitor has passed a lower threshold while decreasing or an upper threshold while increasing respectively with the difference between said upper threshold and said lower threshold having a value substantially proportional to the ratio of the product of said first and second values to the sum of said first and second values so that said oscillating electric signal corresponds to the voltage across said capacitor.

Oscillating circuit comprising:

• a capacitor, a charge circuitry and a control circuitry and characterized in that said charge circuitry includes first and second current generators having respectively first and second current values with opposite directions from each other and switching means designed to couple alternately said generators to said capacitor and in that said control circuitry has a voltage input coupled to said capacitor and an output coupled to control inputs of said switching means and includes a comparator with hysteresis having a lower threshold and an upper threshold and in that the difference between said upper threshold and said lower threshold has a value substantially proportional to the ratio of the product of said first and second values to the sum of said first and second values.