The invention relates generally to oscillators and, more specifically to a surface mount ovenized oscillator assembly.
An oscillator circuit provides a stable-frequency output signal (typically sinusoidal) and, as those skilled in the electronics art will recognize, is an essential component for a variety of electronic devices that include communications equipment, navigation systems, and data processing equipment. Many oscillators employ a piezoelectric quartz crystal as a mechanism for generating and maintaining a stable output signal.
Quartz crystal resonant frequencies are temperature dependent. Stated alternatively, the output frequency of quartz crystals experience frequency shifts that are caused by temperature changes in the quartz element. When used in an oscillator circuit, the quartz crystal can cause the oscillator output frequency to shift as the quartz crystal's temperature changes.
Ovenized oscillators heat the temperature sensitive portions of the oscillator which is isolated from the ambient to a uniform temperature to obtain a more stable output frequency. Ovenized oscillators contain a heater, a temperature sensor, and circuitry to control the heater. The temperature control circuitry holds the crystal and critical circuitry at a precise, constant temperature. The best controllers are proportional, providing a steady heating current which changes with the ambient temperature to hold the oven at a precise set-point, usually about 10 degrees above the highest expected ambient temperature.
The output signal of a quartz crystal oscillator can also be kept steady over temperature by using circuits that sense temperature and which generate an appropriate corrective signal, which keeps the oscillator output frequency stable. Such a circuit is known as a temperature compensated crystal oscillator or “TCXO”. A TCXO is a quartz oscillator that employs active circuitry to generate a compensation signal that is used to keep the output of the oscillator device stable over wide-ranging temperatures. A TCXO can provide a very stable output signal over wide temperature swings and is a preferred oscillator in many communications applications and is the oscillator of choice where highly stable frequency sources are required.
The present invention is directed to a lower cost, easier to manufacture surface mount oscillator assembly incorporating the high performance of an ovenized oscillator with the low cost of a temperature controlled crystal oscillator.
The present invention is generally directed to an oscillator assembly comprised of a base surface mount substrate which includes a top surface and defines a cavity; a component surface mount substrate which includes an oscillator and a heater mounted on a top surface and a temperature control assembly mounted on a bottom surface, the component surface mount substrate being direct surface mounted to the top surface of the base surface mount substrate in a relationship wherein the temperature control assembly is located inside the cavity defined in the base surface mount substrate; an interior lid which is seated on the top surface of the component surface mount substrate and covers both the oscillator and the heater and defines an oven; and an exterior lid which is coupled to the base surface mount substrate and covers the interior lid and the top surface of the base and component surface mount substrates.
In one embodiment, the oscillator is a temperature compensated crystal oscillator.
In one embodiment, the oscillator is a voltage controlled temperature compensated crystal oscillator.
In one embodiment, the base surface mount substrate includes first and second pluralities of surface mount connection pads defined on the top and bottom surfaces thereof respectively and the component surface mount substrate includes a first plurality of surface mount connection pads on the bottom surface thereof for direct surface coupling of the base surface mount substrate to a motherboard and the component surface mount substrate to the base surface mount substrate.
In one embodiment, the heater and a temperature sensor are located in the same case.
In one embodiment, the heater is a transistor and the temperature sensor is a diode.
In one embodiment, the oscillator assembly further comprises a heat transfer element seated on the oscillator for increasing the thermal resistance of the oscillator.
In one embodiment, the oscillator assembly further comprises a heat transfer element seated on both the oscillator and the heater for decreasing the thermal resistance of the oscillator.
The present invention is also directed to an oscillator assembly that comprises an oscillator and a combination heater and temperature sensor assembly located on a first side of a component substrate and a temperature control assembly located on a second opposed side of the component substrate, the combination heater and temperature sensor assembly including a heater and a temperature sensor located together in the same enclosure.
In one embodiment, the oscillator assembly further comprises a base substrate which includes a top surface and defining a cavity, the component substrate being seated on the top surface of the base substrate in a relationship wherein the temperature control assembly is located inside the cavity.
In one embodiment, the oscillator assembly further comprises a first lid covering the oscillator and the combination heater and temperature sensor assembly and a second lid that covers the first lid.
In one embodiment, the oscillator assembly further comprises a heat transfer element seated on the oscillator.
In one embodiment, the heat transfer element is also seated on the combination heater and temperature sensor assembly.
The present invention is further directed to an oscillator assembly that comprises an oscillator on the first surface of a component substrate; a heater on the first surface of the component substrate; and a thermal resistance element seated on the oscillator for adjusting the thermal resistance between the oscillator and the heater.
In one embodiment of the oscillator assembly, the thermal resistance element is seated on the oscillator and the heater for decreasing the thermal resistance between the oscillator and the heater.
In one embodiment, the oscillator assembly further comprises a base substrate which includes a first surface and defines a cavity; a temperature control assembly on a second surface of the component substrate, the component substrate being seated on the first surface of the base substrate and the temperature control assembly being located in the cavity; and a first lid which covers the oscillator and the heater.
In one embodiment, the oscillator assembly further comprises a second lid covering the first lid.
Other advantages and features of the present invention will be more readily apparent from the following detailed description of the preferred embodiment of the invention, the accompanying drawings, and the appended claims.
These and other features of the invention can best be understood by the following description of the accompanying FIGURES as follows:
As shown in
As more particularly shown in
The longitudinally extending vertical side surface/face 24 of the substrate 12 includes three spaced-apart, parallel, and vertically oriented castellations or recesses 32, 34, and 36 (
The opposed longitudinally extending vertical side surface/face 26 of the substrate 12 also includes three spaced-apart, parallel, and vertically oriented conductive castellations or recesses 38, 40, and 42 (
A region or pad or ring 41 of conductive material is formed on the top surface 20 of the base substrate 12, surrounds each of the openings defined by each of respective castellations 32, 34, 36, 38, 40, and 42 in the top surface 20 of the base substrate 12, and is in contact with the conductive material covering each of the respective castellations 32, 34, 36, 38, 40, and 42.
Although not shown in any of the FIGURES, it is understood that a mounting/solder region or pad or ring of conductive material similar to the region or pad 41 is formed on the bottom surface 22 of the base substrate 12, surrounds each of the openings defined by each of the respective castellations 32, 34, 36, 38, 40, and 42 in the bottom surface 22 of the base substrate 12, and is in contact with the conductive material covering each of the respective castellations 32, 34, 36, 38, 40, and 42.
A plurality of additional mounting/solder regions or pads 44 of conductive material are formed on the top surface 20 of the base substrate 12 and are electrically connected to respective ones of the pads 41 of the respective castellations 32, 34, 36, 38, and 42 via respective strips 53 of conductive material also formed on the top surface 20 of the base substrate 12 and extending between respective ones of the pads or rings 41 and respective ones of the pads 44.
The base substrate 12 additionally includes and defines a centrally located and generally rectangularly-shaped cavity or recess 54 (
In accordance with this embodiment, and although not shown in any of the FIGURES, the base substrate 12 is adapted for direct surface mounting onto the top surface of a motherboard in a relationship wherein the mounting/solder pads (not shown) on the bottom surface 22 of the base substrate 12 are abutted and coupled to respective mounting/solder pads (not shown) on the surface of the motherboard (not shown).
As shown in
The longitudinally extending vertical side surface/face 64 of the substrate 14 includes three spaced-apart, parallel, and vertically oriented castellations or recesses 72, 74, and 76 which are covered with a layer of conductive material and extend between, and normal to, the top and bottom surfaces 60 and 62 respectively of the substrate 14. In the embodiment shown, the two castellations 72 and 74 are located adjacent the transverse side surface/face 68 of the substrate 14 and the transverse castellation 76 is located adjacent the side surface/face 70 of the substrate 14.
The opposed longitudinally extending vertical side surface/face 66 of the substrate 14 includes two spaced-apart, parallel, and vertically oriented castellations or recesses 80 and 82 which are covered with a layer of conductive material and extend between, and in an orientation generally normal to the top and bottom surfaces 60 and 62 respectively of the substrate 14. In the embodiment shown, the castellation 80 is located adjacent the transverse side surface/face 68 of the substrate 14 in a relationship diametrically opposed to the castellation 72 defined in the longitudinally extending vertical side surface/face 66 and the castellation 82 is located adjacent the opposed transverse side surface/face 70 in a relationship diametrically opposed to the castellation 76 defined in the longitudinally extending side surface/face 66 of the substrate 14.
A region or pad or ring 84 of conductive material is formed on the top surface 60 of the substrate 14, surrounds each of the respective openings defined by each of the castellations 72, 74, 76, 80, and 82 in the top surface 60 of the substrate 14, and is in contact with the conductive material covering the surface of each of the castellations 72, 74, 76, 80, and 82.
Similarly, a mounting/solder region or pad 86 of conductive material is formed on the bottom surface 62 of the substrate 14, surrounds each of the respective openings defined by each of the castellations 72, 74, 76, 80, and 82 in the bottom surface 62 of the substrate 14, and is in contact with the conductive material covering the surface of each of the castellations 72, 74, 76, 80, and 82.
The substrate 14 additionally defines and includes a pair of spaced-apart, parallel, and generally oval-shaped slits 90 and 92 that extend through the substrate 14 in a relationship and orientation generally normal to the opposed longitudinally extending side surfaces/faces 64 and 66 of the substrate 14.
The slit 90 is located in the substrate 14 adjacent and parallel to the transverse side surface/face 68 of the substrate 14 and in a relationship generally co-linear with the castellation 82 defined in the longitudinally extending side surface/face 64 of the substrate 14, The slit 92 is located in the substrate 14 adjacent and parallel to the opposed transverse side surface/face 70 of the substrate 14.
In the embodiment shown, the castellations 72 and 80 are located on the substrate 14 between the transverse side surface/face 68 and the slit 90 on the substrate 14; the castellation 74 is positioned generally co-linearly with the slit 90; and the castellations 76 and 82 are located on the substrate 14 between the slit 92 and the transverse side surface/face 70 of the substrate 14.
An oscillator 100 (
A combination oven heater and temperature sensor assembly 110 (
In the embodiment shown, and with reference to
The substrate 14 also includes an oscillator temperature control assembly 120 (
Thus, in the embodiment shown, the oscillator 100 and heater and temperature sensor assembly 100 on the one hand and the elements 122, 124, and 126 of the temperature control assembly 120 on the other hand are located, seated, and mounted on and to opposite sides of the substrate 14.
Although not shown or described herein in any detail, it is also understood that a plurality of additional strips of conductive material are formed on both the top and bottom surfaces 60 and 62 of the substrate 14 for connecting the various components on the top and bottom surfaces 60 and 62 of the component substrate 14 to each other and to respective ones of the castellations 72, 74, 76, 80, and 82 on the substrate 14 and for electrically interconnecting the oscillator and heater components on the top surface 60 of the substrate 14 to the temperature control components on the bottom surface 62 of the substrate 14.
As shown in
As shown in
The lid/cover 16 which, in the embodiment shown, is generally rectangularly- and box-shaped, is made of a suitable insulative material such as, for example, PEEK, and includes a flat horizontal roof 130 and four sides 132, 134, 136, and 138 which depend downwardly normally from the four respective peripheral edges of the roof 130 and terminate in four respective distal peripheral end faces abutted and mounted on and against the top surface 60 of the substrate 14. Each of the sides 132 and 134 additionally includes and defines a distal tab 133 (only one of which is shown in
In the embodiment shown, the lid/cover 16 is seated on and against the portion of the substrate 14 bounded generally by and between the two transverse slits 90 and 92 and the two opposed longitudinally extending side surfaces/faces 64 and 66 of the substrate 14 in a relationship wherein the respective distal peripheral end faces of the lid/cover 16 are abutted and secured, as by gluing or the like, to the top surface 60 of the substrate 14 and the respective tabs 133 on the lid/cover 16 extend into the respective slits 90 and 92.
In the position of the lid/cover 16 as shown in
Referring to
The external lid/cover 18 which, in the embodiment shown, is also generally rectangularly- and box-shaped, is also made of a suitable insulative material such as, for example, PEEK and includes a flat horizontal roof 150 and four sides 152, 154, 156, and 158 which depend and extend normally downwardly from the four respective peripheral edges of the roof 150 and terminate in four respective distal peripheral end faces abutted against the top surface 20 of the substrate 12.
In the embodiment as shown in
In accordance with the operation of the oscillator assembly 10 of the present invention, the dissipated power of the heater 111 of the heater/temperature sensor assembly 110 is proportionally controlled to heat and maintain a constant temperature inside the oven 123 (
When the temperature is below the selected set point for the oven 123, the temperature control assembly 120 increases power supplied through the power terminal 180 and circuit line 185 in
When the temperature is above the set point for the oven 123, the temperature control assembly 120 reduces power to the heater 111 to allow a decrease in the temperature in the oven 123.
As shown in
Further, in accordance with the operation of the oscillator assembly 10 of the present invention, the external lid/cover 18 provides a second layer or zone or region 190 (
Still further, as a result of the placement and seating of both the oscillator 100 and the heater/temperature sensor assembly 110 in close proximity to each other on the same side of the substrate 14, it is understood that there is a thermal resistance between the oscillator 100 and the heater/temperature sensor assembly 110. This thermal resistance must be compensated to assure the proper operation and performance of the oscillator assembly 10.
Oscillators in use today include complex electronic temperature compensation circuits. The present invention, however, includes the use of thermal resistance/temperature compensation/heat transfer elements 200 (
The thermal resistance element embodiment 200 as shown in
In this setting, thermal resistance needs to be added or increased, and the element 200 acts as a heat sink by allowing for the transferring of excess heat from the oscillator 100 into the element 200, thereby reducing the temperature of the oscillator 100 to the desired temperature.
The size of the element 200 can be adjusted as desired to adjust the amount of heat transferred into the element 200, and thus adjust and control he amount by which the temperature of the oscillator 100 is reduced, and thus adjust and control the amount by which the thermal resistance of the oscillator 100, and thus the thermal resistance between the oscillator 100 and the heater/temperature sensor assembly 110, is increased.
The thermal resistance element embodiment 202 shown in
In this setting, the thermal resistance needs to be subtracted, i.e., thermal resistance between the oscillator 100 and the heater/temperature sensor assembly 100 needs to be reduced, and the element 202 acts as a heat conductive bridge that allows for heat generated by the heater/temperature sensor assembly 110 to be transferred from the heater/temperature sensor assembly 110 to the element 202 and then from the element 202 to the oscillator 100 for increasing the temperature of the oscillator 100 to the desired temperature.
The size of the element 202 can be adjusted as desired to adjust the amount of heat transferred into the element 202 from the heater/temperature sensor assembly 110 and then back into the oscillator 100, and thus adjust and control the amount by which the temperature of the oscillator 100 is increased, and thus adjust and control the amount by which the thermal resistance of the oscillator 100, and thus the thermal resistance between the oscillator 100 and the heater/temperature sensor assembly 110, is decreased.
While the invention has been taught with specific reference to the embodiments shown, it is understood that a person of ordinary skill in the art will recognize that changes can be made in form and detail without departing from the spirit and the scope of the invention. The described embodiments are to be considered in all respects only as illustrative and not restrictive.
This application claims the benefit of the filing date and disclosure of U.S. Provisional Application Ser. No. 61/654,144, filed on Jun. 1, 2012 which is explicitly incorporated herein by reference as are all references cited therein.
Number | Date | Country | |
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61654144 | Jun 2012 | US |