Crystal clock generator operating at third overtone of crystal's fundamental frequency (US7002423)

an oscillating crystal having a fundamental frequency of oscillation but forced to oscillate at a third overtone of the fundamental frequency, the third overtone being a frequency of about three times the fundamental frequency;

the oscillating crystal coupled between a first input node and a second input node;

a first amplifier circuit having an input attached to the first input node and generating a first output, the first amplifier also having a first phase-shift node;

a second amplifier circuit having an input attached to the second input node and generating a second output, the second amplifier also having a second phase-shift node;

a tuning resistor coupled between the first input node of the first amplifier and the second input node of the second amplifier, the tuning resistor having a value such that an absolute value of a product (gm�Xc1�Xc2) is greater than an effective impedance of the oscillating crystal, wherein gm is a gain of the first amplifier circuit and gm is also the gain of the second amplifier circuit, and Xc1 is an effective reactance of an equivalent capacitance on the first input node of the first amplifier and Xc1 is also an effective reactance of an equivalent capacitance on the second input node of the second amplifier, and Xc2 is an effective reactance of an equivalent capacitance on the first phase-shift node of the first amplifier and Xc2 is also the effective reactance of the equivalent capacitance on the second phase-shift node of the second amplifier;

a multiplier, coupled to the first amplifier circuit and to the second amplifier circuit, for generating a doubled output from the first output and from the second output, the doubled output having an output frequency that is double the third overtone and about six times the fundamental frequency of the oscillating crystal; and

an output filter, attached to the doubled output, for attenuating signals having a frequency of the third overtone, but for passing signals having the output frequency,

whereby the oscillating crystal is forced to oscillate at the third overtone, while the doubled output is six times the fundamental frequency of the oscillating crystal.

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Patent	Pub.Date	Inventor	Assignee	Title
US4388626	1983-06	Gans	Bell Telephone Laboratories, Incorporated	Phased array antennas using frequency multiplication for reduced numbers of phase shifters
US4661785	1987-04	Benjaminson	S. T. Research Corporation	Balanced feedback oscillators
US5126694	1992-06	Montress et al.	Raytheon Company	Phase locked oscillator
US5263197	1993-11	Manjo et al.	Matsushita Communication Industrial Corporation of America	Dual port oscillator for two-stage direct conversion receiver
US6057740	2000-05	Consolazio et al.	Northrop Grumman Corporation	Local oscillator system using harmonic derived from phase locked loop
US6091307	2000-07	Nelson	Lucent Techmologies Inc.	Rapid turn-on, controlled amplitude crystal oscillator
US6169459	2001-01	Wessendorf	Sandia Corporation	Active-bridge oscillator
US6667666	2003-12	Uzunoglu	Aeschlimann; Anthony	Synchronous oscillators
US6677862	2004-01	Houlihane et al.	SchlumbergerSema Inc.	Transmitter tolerant to crystal variations
US20030134610A1	2003-07	DiCamillo		Frequency scalable, low self-generated noise frequency source