TEMPERATURE COMPENSATED CRYSTAL OSCILLATOR

• US 3,821,665 A
• Filed: 06/11/1973
• Issued: 06/28/1974
• Est. Priority Date: 06/11/1973
• Status: Expired due to Term

• Current Assignee: Irwin J, Morton J
• Original Assignee: Irwin J, Morton J
• Inventors: IRWIN J, MORTON J
• Application Number:
  US05/369,047
• Time in Patent Office: 382 Days
• US Class Current: 331/116.00R
• CPC Class Codes: H03B 2200/0018 relating to the cutting angle of a crystal, e.g. AT cut quartz
• CPC Class Codes: H03B 2200/004 including a variable capacitance, e.g. a varicap, a varactor or a variable capacitance of a diode or transistor
• CPC Class Codes: H03B 5/368 the means being voltage variable capacitance diodes
• CPC Class Codes: H03L 1/023 by using voltage variable capacitance diodes

Abstract

An oscillator having a frequency determining crystal connected therein which produces a frequency deviation with temperature defined by a formula including first, second and third order terms and a varactor connected to said oscillator for varying the frequency of said oscillator in response to a voltage produced by a function generating means which produces a frequency variation of the varactor that is equal to and the inverse of the frequency deviation of the oscillator so that the total effect of temperature variations on the circuit is little or no frequency deviations with ambient temperature changes.

Claims

1. A temperature compensated crystal oscillator comprising:

a. an oscillator having a frequency determining crystal connected therein;

b. voltage variable reactance means connected to said oscillator for varying the frequency of said oscillator in response to a voltage applied to said reactance means;

c. generating means providing a voltage which varies linearly with temperature;

d. first multiplying means coupled to said generating means for providing a voltage which is the square of the voltage from said generating means;

e. second multiplying means coupled to said generating means for providing a voltage which is the cube of the voltage from said generating means; and

f. summing means coupled to said generating means, said first multiplying means, said second multiplying means and said voltage variable reacTance means for supplying a voltage to said reactance means proportional to the sum of the voltages from said generating means and said first and second multiplying means.

2. A temperature compensated crystal oscillator as claimed in claim 1 including in addition three scaling factor means coupling the generating means and the first and second multiplying means to the summing means, respectively, for providing the linear, square and cube voltages each with a predetermined amplitude to provide a sum voltage which controls the reactance means to vary the frequency of the oscillator the inverse of variations of the oscillator due to temperature changes thereof.

3. A temperature compensated crystal oscillator as claimed in claim 2 wherein the scaling factor means each include variable means for varying the output amplitude of voltages applied thereto.

4. A temperature compensated crystal oscillator as claimed in claim 1 wherein the crystal is an AT cut quartz crystal.

5. A temperature compensated crystal oscillator comprising:

a. an oscillator having a frequency determining crystal connected therein;

b. voltage variable reactance means connected to said oscillator for varying the frequency of said oscillator in response to a voltage applied to said reactance means; and

c. function generating means connected to supply a control voltage to said reactance means for varying the frequency of said oscillator inversely to variations in the frequency of said oscillator caused by variations in temperature of said oscillator, said function generating means including a linear generator and at least one multiplier for producing higher order terms proportional to the frequency variations of said oscillator due to the variations in temperature of said oscillator.