Abstract: A voltage-controlled-oscillator with a modulator, comprising a first variable capacitance diode and a second variable capacitance diode. The first variable capacitance diode is connected in series with the second variable capacitance diode to form a resonance device, wherein capacitance of the first variable capacitance diode is controlled by applying a reverse bias voltage and an oscillation frequency control voltage to both ends of the first variable capacitance diode, and capacitance of the second variable capacitance diode is controlled in a reverse direction to changes in the capacitance of the first variable capacitance diode with respect to the oscillation frequency control voltage by applying the oscillation frequency control voltage and a modulation signal to both ends of the second variable capacitance diode to thereby provide a frequency modulated wave.

Abstract: A voltage-controlled-oscillator with a modulator, comprising a first variable capacitance diode, a second variable capacitance diode, and a third variable capacitance diode. The second variable capacitance diode is connected in series with the third variable capacitance diode to form a serial connection member.

Abstract: A crystal oscillator circuit that is temperature compensated over a broad temperature range has a crystal oscillator, a reactance compensation circuit for providing temperature compensation at low temperatures, and a control voltage-generating circuit for providing temperature compensation at high temperatures. The reactance compensation circuit includes the parallel combination of a thermistor and a variable-capacitance diode, and this parallel combination is connected in series with the crystal oscillator. The control voltage-generating circuit includes a thermistor and transistors and applies a voltage corresponding to the ambient temperature to the variable-capacitance diode of the reactance compensation circuit.