Abstract:
A small crystal oscillator with metal packaging includes a small size crystal oscillator circuit, a body encompassing the small size crystal oscillator circuit, first and second terminal leads coupled to the crystal oscillator circuit through the body, metal packaging encompassing at least a portion of the body, and a ground connection electrically coupled to the metal packaging. The invention includes a variety of shapes and configurations for the metal packaging and a variety of pin configurations.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims priority to U.S. Provisional Application No. 60/573,835, filed May 25, 2004, entitled “Small Crystal With Grounded Package,” which is incorporated herein by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The invention relates generally to crystal oscillators and, more particularly, to relatively small size crystal oscillators with metal packaging.  
         [0004]     2. Related Art  
         [0005]     Conventional crystal oscillators include relatively large crystal oscillators, commonly referred to as HC-49U crystal oscillators (hereafter, “large crystals”), and relatively small crystal oscillators, commonly referred to as HC-49US crystal oscillators (hereafter, “small crystals”). Large crystal oscillators are available in ceramic or metal packaging. The metal packaging can be grounded to protect surrounding components from electromagnetic interference (“EMI”) from the crystal. The grounded metal packaging also protects the crystal from externally generated EMI.  
         [0006]     Small crystal oscillators occupy less physical space and generally have a smaller footprint than large crystal oscillators. Conventional small crystal oscillators are presently available only in ceramic packaging, not metal packaging.  
         [0007]     Crystal oscillator circuits utilized in small crystal oscillators are physically different than crystal oscillator circuits utilized in large crystal oscillators. As a result, the physical size of a crystal oscillator package is a function of the type of crystal utilized within. The physical size of a crystal oscillator package is, therefore, not simply a manufacturing or design choice.  
         [0008]     What is needed, therefore, are relatively small crystal oscillators with metal packaging.  
       SUMMARY OF THE INVENTION  
       [0009]     The present invention is directed to relatively small crystal oscillators with metal packaging. The invention includes a variety of shapes and configurations for the metal packaging and a variety of pin configurations.  
         [0010]     A small crystal oscillator in accordance with one embodiment of the present invention includes a small size crystal oscillator circuit, a body encompassing the small size crystal oscillator circuit, first and second terminal leads coupled to the crystal oscillator circuit through the body, metal packaging encompassing at least a portion of the body, and a ground connection electrically coupled to the metal packaging.  
         [0011]     Additional features and advantages of the invention will be set forth in the description that follows. Yet further features and advantages will be apparent to a person skilled in the art based on the description set forth herein or may be learned by practice of the invention. The advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.  
         [0012]     It is to be understood that both the foregoing summary and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES  
       [0013]     The present invention will be described with reference to the accompanying drawings, wherein like reference numbers indicate identical or functionally similar elements. In the drawings:  
         [0014]      FIG. 1A  is a top plan view of an exemplary large crystal oscillator and an exemplary small crystal oscillator.  
         [0015]      FIG. 1B  is a side view of the small crystal oscillator, taken along the line A illustrated in  FIG. 1A .  
         [0016]      FIG. 1C  is a side view of the small crystal oscillator, taken along the line B illustrated in  FIG. 1A .  
         [0017]      FIG. 2A  is a cut-away top plan view of the small crystal oscillator, wherein the metal packaging encompasses an upper portion of the body.  
         [0018]      FIG. 2B  is a side view of the small crystal oscillator, taken along the line A illustrated in  FIG. 2A .  
         [0019]      FIG. 2C  is a side view of the small crystal oscillator, taken along the line B illustrated in  FIG. 2A .  
         [0020]      FIG. 3A  is a top plan view of the small crystal oscillator, including a ribbon-type ground terminal.  
         [0021]      FIG. 3B  is a side view of the small crystal oscillator, taken along the line A illustrated in  FIG. 3A .  
         [0022]      FIG. 3C  is a side view of the small crystal oscillator, taken along the line B illustrated in  FIG. 3A . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0023]     The present invention is directed to relatively small crystal oscillators with metal packaging. The invention includes a variety of shapes and configurations for the metal packaging and a variety of pin configurations.  
         [0024]      FIG. 1A  is a top plan view of an exemplary large crystal oscillator  100  and an exemplary small crystal oscillator  200 . The large crystal oscillator  100  includes a body  106 , enclosing a large crystal oscillator circuit. The large crystal oscillator  100  further includes terminal leads  102  and  104 , a metal package  108 , and a ground lead  110  protruding therefrom.  
         [0025]     The small crystal oscillator  200  includes a body  206 , enclosing a small crystal oscillator circuit. The small crystal oscillator  200  further includes terminal leads  202  and  204 , a metal package  208 , and a ground lead  210  protruding therefrom.  
         [0026]     In the example of  FIG. 1 , the large crystal oscillator  100  is a distance “x” longer or taller than small crystal oscillator  200 . The distance x is illustrated for exemplary purposes. In practice, the distance x is relative. Large and small crystal oscillators are distinguished from one another primarily by the type of crystal oscillator circuit within, as is known to those skilled in the art.  
         [0027]     With respect to the small crystal oscillator  200 , the metal packaging  208  is coupled to ground through ground lead  210 . The metal packaging  208  protects surrounding components from electromagnetic interference (“EMI”) generated by the small crystal oscillator circuit within the body  206 . The grounded metal packaging  208  also protects the small crystal oscillator circuit from externally generated EMI.  
         [0028]     The small crystal oscillator  200  can have, for example, and without limitation, a round cylindrical shape, an oval-cylindrical shape, or any of a variety of other shapes. For example,  FIG. 1B  is a side plan view of the small crystal oscillator  200 , taken along the line A illustrated in  FIG. 1A .  FIG. 1C  is a side view of the small crystal oscillator  200 , taken along the line B illustrated in  FIG. 1A . In the examples of  FIGS. 1A-1C , the small crystal oscillator  200  has an oval-cylindrical shape.  
         [0029]     The metal package  208  can encompass the entire body  206 , or portions thereof. Covering portions of the body  206  with the metal packaging  208 , rather than covering the entire body  206 , can be utilized, for example, to reduce the quantity of metal needed, and/or to obtain desired EMI blocking characteristics.  
         [0030]     For example,  FIG. 2A  is a cut-away top plan view of the small crystal oscillator  200 , wherein the metal packaging  208  encompasses an upper portion  212  of the body  206 .  FIG. 2B  is a side view of the small crystal oscillator  200  illustrated in  FIG. 2A . Alternatively, the metal packaging  208  can be manufactured to encompass a lower portion  214  of the body  206 , and/or one or more side portions of the body  206 .  
         [0031]     The location of the terminal leads  202  and  204 , and the ground lead  210 , relative to one another and relative to the body  206 , is variable. In the example of  FIGS. 1A-1C , and  2 A- 2 C, the terminal leads  202  and  204  extend from a first end of the small crystal oscillator  200 , and the ground lead  210  extends from a second end of the small crystal oscillator  200 , which is opposite from the first end. The invention is not, however, limited to this configuration.  
         [0032]     The ground terminal  210  can be formed in any of a variety of shapes.  
         [0033]     For example, and without limitation, the ground terminal  210  can be fabricated as a wire-type terminal, as illustrated in  FIGS. 1A-1C , or as a ribbon-type terminal, as illustrated in  FIGS. 2A-2C .  
         [0034]     The terminal leads  202  and  204 , and the ground terminal  210  can be designed for surface mounting or “through-the-hole” mounting on a circuit board.  
         [0035]     The terminal leads  202  and  204 , and the ground terminal  210  can be shaped so that the small crystal oscillator  200  is mounted in a lay-down position, as illustrated in  FIGS. 1A-1C , and  2 A- 2 C, or in an upright position, as illustrated in  FIGS. 3A-3C .  
         [0036]      FIG. 3B  is a side view of the small crystal oscillator, taken along the line A illustrated in  FIG. 3A .  FIG. 3C  is a side view of the small crystal oscillator, taken along the line B illustrated in  FIG. 3A .  
       CONCLUSION  
       [0037]     The present invention has been described above with the aid of functional building blocks illustrating the performance of specified functions and relationships thereof. The boundaries of these functional building blocks have been arbitrarily defined herein for the convenience of the description. Alternate boundaries can be defined so long as the specified functions and relationships thereof are appropriately performed. Any such alternate boundaries are thus within the scope and spirit of the claimed invention. One skilled in the art will recognize that these functional building blocks can be implemented by discrete components, application specific integrated circuits, processors executing appropriate software and the like and combinations thereof.  
         [0038]     While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.