Amplitude modulated crystal oscillator

Claim 2

A circuit for producing amplitude modulated waves, which includes: oscillator means having an output for generating a periodic signal; a tuning circuit including an inductance having a center tap connected to said output of said oscillator means and a pair of unilaterally conductive semiconductor devices of variable capacitance connected in series opposition across said inductance; and means for applying a modulating input signal to said pair of unilaterally conductive semiconductor devices to vary the capacitance of said semiconductor devices and amplitude modulate the periodic signal generated by said oscillator means.

Claim 3

The circuit of claim 1, wherein: said oscillator means comprises a crystal oscillator for generating a sinusoidal signal of a fixed frequency; and said pair of unilaterally conductive devices comprises a pair of diodes, the capacitance of which may be varied in response to a modulating input signal to amplitude modulate the sinusoidal signal.

Claim 4

The circuit of claim 2, wherein: said diodes are varactor diodes, and said modulating input signal is a reverse bias voltage applied to said diodes to vary the capacitance of said diodes.

Claim 5

A circuit for producing amplitude modulated waves, which comprises: oscillator means having an output for generating a periodic signal; a tank circuit including an inductance having a center tap connected to said output of said oscillator means and a voltage variable capacitance load comprising a pair of semiconductor diodes connected in series opposition across said inductance; and means for applying a modulating voltage to said load to vary the capacitance of said diodes and amplitude modulate the periodic signal generated by said oscillator means.

Claim 6

A circuit for producing amplitude modulated waves, which comprises: oscillator means having an output for generating a periodic signal; a tank circuit including an inductance having a center tap connected to said output of said oscillator means and a voltage variable capacitance load comprising a pair of semiconductor diodes connected in series opposition across said inductance; and means for applying a modulating voltage to said load to vary the capacitance of said diodes and amplitude modulate the periodic signal generated by said oscillator means.

Claim 7

The circuit of claim, 4 wherein: said oscillator means comprises a crystal oscillator.

Claim 8

The circuit of claim 4, wherein: said pair of semiconductor diodes comprises a pair of varactor diodes having a capacitance which varies in response to the modulating voltage applied to said varactor diodes.

Claim 9

The circuit of claim 6, wherein: the modulating voltage applied to said varactor diodes is a reverse bias voltage which varies the impedance of said tank circuit.

Claim 10

A circuit for producing amplitude modulated waves, which includes: a crystal oscillator means having an output for generating a sinusoidal signal having a fixed frequency; a tuning circuit including a center-tapped inductance connected at its center tap to said oscillator output and a pair of voltage variable capacitance diodes having cathode terminals connected together at a common terminal and anode terminals connected to opposite ends of said inductance; and means for applying a modulating voltage to said common terminal to vary the capacitance of said diodes to modulate the amplitude of the sinusoidal signal generated by said oscillator means.

Claim 11

A circuit for producing amplitude modulated waves, which includes: a crystal oscillator means having an output for generating a sinusoidal signal having a fixed frequency; a tuning circuit including a center-tapped inductance connected at its center tap to said oscillator output and a pair of voltage variable capacitance diodes having cathode terminals connected together at a common terminal and anode terminals connected to opposite ends of said inductance; and means for applying a modulating voltage to said common terminal to vary the capacitance of said diodes to modulate the amplitude of the sinusoidal signal generated by said oscillator means.

Claim 12

The circuit of claim 8, wherein: said voltage variable capacitance diodes are semiconductor diodes, the capacitances of which vary with the voltage of their cathode terminals.

Claim 13

The circuit of claim 9, wherein: the modulating voltage applied to said common terminal constitutes a reverse bias voltage for the semiconductor diodes.