Electronic oscillator with transmission line tuning of phase noise and linearity
AssigneeMicronetics, Inc.
InventorsDavid F. Robbins, Richard J. Landry
Life of this patent
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Abstract
An improved electronic oscillator of limited bandwidth for better phase noise and linearity characteristics, and method for production, where a transmission line of specific characteristics is introduced between major components of the frequency source to significantly improve phase noise and linearity, and minor adjustments to the L/C ratio of the transmission line during production testing further optimize phase noise and linearity without adverse effects on other circuit parameters. The improvement chiefly relates to the length, configuration and accessibility of a transmission line connecting a resonator and main tuning capacitor in a series resonant tank circuit of an oscillator.
Claims20
An electronic oscillator of limited bandwidth comprising:
- a resonant tank circuit including a resonator, a transmission line, a main capacitor, and a positive feedback signal for producing oscillations at a resonant frequency, said transmission line being at least one sixteenth (1/16) and not more than three sixteenths (3/16) wavelengths of said resonant frequency and configured to provide a conductive path between said resonator and said main capacitor;
- and
- a signal amplifier for overcoming losses to sustain oscillations in said tank circuit, said amplifier having an input and a feedback output, said amplifier being connected in a feedback loop for said tank circuit.
A voltage-controlled electronic oscillator of limited bandwidth comprising:
- a resonant tank circuit including a ceramic resonator, a transmission line, a varactor diode, a positive feedback signal for producing oscillations at a resonant frequency, said transmission line being at least one sixteenth (1/16) and not more than three sixteenths (3/16) wavelengths long and configured as a land on a substrate of uniform dielectric constant on a circuit board to provide a conductive path between said resonator and anode end of said varactor diode;
- a signal amplifier for overcoming losses to sustain oscillations in said tank circuit, said amplifier having an input and a feedback output, said amplifier being connected in a feedback loop for said tank circuit;
- and
- a coupling capacitor connected between said amplifier and said varactor diode, wherein capacitive value of said varactor diode is much larger than capacitive value of said coupling capacitor so that said resonant frequency is primarily dependent on capacitive value of said varactor diode;
- said land of said transmission line being longer than distance between end points of said land, width of said land being in a range of forty to fifty thousandths (0.040-0.050) inch, component layout of said circuit board configured to allow physical access to said transmission line after said board is populated with components.
A method for manufacturing electronic oscillators of limited bandwidth with improved, consistent phase noise and linearity characteristics comprising:
- making a land on a substrate of uniform dielectric constant on a circuit board as a transmission line for connecting a resonator and a main tuning capacitor in a series resonant tank circuit of said oscillator, said transmission line being at least one sixteenth (1/16) and not more than three sixteenths (3/16) wavelengths of resonant frequency of said oscillator.
Dependencies are inferred from the claim text.