Abstract: To extend the variation range of a controlled frequency oscillator comprising a piezoelectric element, a lithium tantalate or lithium niobate element is used in parallel with which there is connected a linearization circuit comprising an inductance in series with a parallel circuit comprising a resistor and a capacitor.

Abstract: A frequency regulated crystal oscillator with (1) an oscillating circuit made up of an amplifier, piezoelectric crystal and voltage controls capacitor, and (2) a two-part compensating circuit connected to the terminals of the variable capacitor, each part having thermistors whose resistance varies with temperature to produce complementary signals and which are shunted with electrical resistors.

Abstract: An oscillator formed of an amplifier with a feedback loop containing two parallel connected crystals in series with a voltage variable capacitance. The two crystals have respective resonance frequencies above and below the limits of a wide band over which the oscillator frequency can be varied by a control voltage. Frequency versus control voltage linearity is improved by inductances inserted in parallel and in series, respectively, with the lower and higher frequency crystals.

Abstract: A crystal-controlled oscillator whose frequency is regulated as a function of temperature and having a feedback loop with a capacitor whose capacitance is electrically variable, to which capacitor a variable electrical compensating signal varying in accordance with a third-degree law as a function of temperature, is applied. The compensating circuit in accordance with the invention produces a signal of this kind at its terminals by three units respectively comprising three thermistors R.sub.T1, R.sub.T2, R.sub.T3, each unit being specifically designed to create the signal corresponding to a given arcuate portion of the total graph function. The applications are in particular in the field of portable radio transmitters.