Crystal oscillator with minimized Q reduction

An oscillator circuit, comprising:

• a resonant circuit;
• an amplifier operably coupled to the resonant circuit and adapted to oscillate at a frequency determined by the resonant circuit, wherein the amplifier appears as a negative resistance to the resonant circuit, such that the magnitude of the negative resistance is greater than that of a resistance associated with the resonant circuit;
• a current source adapted to provide a bias current to the resonant circuit for maintaining a consistent voltage swing across the resonant circuit without any substantial reduction in the quality factor (Q) of the resonant circuit;
• and
• wherein the current source is produced from a transconductance amplifier, that employs feedback to maintain the resonant circuit at an operating point determined by a reference voltage applied to an input of the transconductance amplifier.

An oscillator circuit, comprising:

• a resonant circuit;
• an amplifier operably coupled to the resonant circuit and adapted to oscillate at a frequency determined by the resonant circuit, wherein the amplifier appears as a negative resistance to the resonant circuit, such that the magnitude of the negative resistance is greater than that of a resistance associated with the resonant circuit;
• a current source adapted to provide a bias current to the resonant circuit for maintaining a consistent voltage swing across the resonant circuit without any substantial reduction in the quality factor (Q) of the resonant circuit;
• and
• further comprising an automatic gain control circuit that varies the gain of the amplifier to regulate an amplitude of an output signal generated by the oscillator circuit.

An oscillator circuit, comprising:

• a resonant circuit;
• an amplifier operably coupled to the resonant circuit and adapted to oscillate at a frequency determined by the resonant circuit, wherein the amplifier appears as a negative resistance to the resonant circuit, such that the magnitude of the negative resistance is greater than that of a resistance associated with the resonant circuit;
• a current source adapted to provide a bias current to the resonant circuit for maintaining a consistent voltage swing across the resonant circuit without any substantial reduction in the quality factor (Q) of the resonant circuit;
• and
• wherein the amplifier receives positive feedback at the frequency determined by the resonant circuit and negative feedback at all other frequencies.

A method for producing an oscillating signal, comprising:

• initiating oscillation of an oscillator at a frequency determined by a resonant circuit coupled to the oscillator, wherein the oscillator comprises an oscillator amplifier;
• applying positive feedback to the oscillator amplifier at the frequency determined by the resonant circuit, and applying negative feedback at all other frequencies;
• and
• inputting a bias current from a current source to the resonant circuit while maintaining a consistent voltage swing across the resonant circuit, without any substantial reduction in the quality factor (Q) of the resonant circuit.