Filter structure including circuit board

Abstract

A cavity filter assembly is provided with at least one structural cavity wall comprising a circuit board. The circuit board may also contain other circuits and circuit elements such as trim capacitors, inductors, low noise amplifier circuits and power amplifiers that are part of the filter's function. Input and output coupling structures and connectors may also be provided on the circuit board. The circuit board may contain inter-stage coupling circuits, signal traces, and coupling pads/structures. Further embodiments are provided that incorporate test connectors and directional couplers on the circuit board. In yet other embodiments the filter's electrical characteristics are tunable with trim elements mounted on the circuit board, such as capacitors or inductors, in either mechanical or electrical manner. The filter's electrical characteristics may also be tunable with mechanical elements mounted through the circuit board.

1 . A filter assembly, comprising: 
 an enclosure having at least one cavity;    at least one wall of the enclosure comprised of a circuit board;    a trace formed on the circuit board; and    at least one circuit element, coupled to the trace.    
   
   
       2 . The filter assembly of  claim 1 , wherein the circuit board further comprises a ground plane on a surface of the circuit board that forms a portion of the inner surface of the enclosure.  
   
   
       3 . The filter assembly of  claim 1 , wherein the circuit board further comprises multiple circuit trace layers.  
   
   
       4 . The filter assembly of  claim 1 , wherein the at least one circuit element further comprises a low pass filter.  
   
   
       5 . The filter assembly of  claim 4 , wherein the low pass filter further comprises one of a circuit trace filter element and a mechanical structure filter element.  
   
   
       6 . The filter assembly of  claim 1 , wherein the filter assembly further comprises: 
 an input connector attached to the enclosure and coupled to the at least one cavity; and    an output connector attached to the enclosure and coupled to the at least one cavity.    
   
   
       7 . The filter assembly of  claim 1 , wherein the filter assembly further comprises: 
 an input connector attached to the circuit board and coupled to the at least one cavity; and    an output connector attached to the circuit board and coupled to the at least one cavity.    
   
   
       8 . The filter assembly of  claim 1 , wherein the at least one circuit element further comprises an amplifier and wherein the filter assembly further comprises: 
 an input connector attached to the circuit board and coupled to the at least one cavity;    an output connector attached to the circuit board coupled to an output of the amplifier; and    an output coupling pad mounted in the at least one cavity and coupled to an input of the amplifier.    
   
   
       9 . The filter assembly of  claim 1 , wherein the at least one circuit element further comprises an amplifier and wherein the filter assembly further comprises: 
 an input connector attached to the circuit board and coupled to an input of the amplifier;    an input coupling pad mounted in the at least one cavity and coupled to an output of the amplifier; and    an output connector attached to the circuit board coupled to the at least one cavity.    
   
   
       10 . The filter assembly of  claim 1 , wherein the filter assembly further comprises: 
 a first and a second low noise amplifier;    an input connector attached to the circuit board and coupled to an input of the first low noise amplifier;    an input coupling pad mounted in the at least one cavity and coupled to an output of the first low noise amplifier;    an output coupling pad mounted in the at least one cavity and coupled to an input of the second low noise amplifier; and    an output connector attached to the circuit board coupled to an output of the second low noise amplifier.    
   
   
       11 . A filter assembly, comprising: 
 an enclosure having a cavity;    at least one wall of the enclosure comprised of a circuit board; and    at least one diagnostic circuit formed on the circuit board.    
   
   
       12 . The filter assembly of  claim 11 , further comprising: 
 a trace formed on the circuit board; and    at least one circuit element, coupled to the trace.    
   
   
       13 . The filter assembly of  claim 11 , wherein the diagnostic circuit formed on the circuit board further comprises a signal tap.  
   
   
       14 . The filter assembly of  claim 11 , wherein the diagnostic circuit formed on the circuit board further comprises a directional coupler, comprising: 
 a signal line with an RF signal; and    a sampling line, wherein the sampling line is run in parallel to the signal line and is physically proximate.    
   
   
       15 . The filter assembly of  claim 14 , wherein the directional coupler further comprises a terminating resistance.  
   
   
       16 . The filter assembly of  claim 14 , wherein the directional coupler further comprises a stub terminator.  
   
   
       17 . The filter assembly of  claim 14 , wherein the sampling line is implemented on a surface of the circuit board.  
   
   
       18 . The filter assembly of  claim 14 , wherein the sampling line is implemented on an internal layer of the circuit board.  
   
   
       19 . The filter assembly of  claim 14 , wherein the sampling line is implemented on a same circuit layer as the signal line.  
   
   
       20 . The filter assembly of  claim 14 , wherein the sampling line is implemented on a first circuit layer and the signal line is implemented on a second circuit layer.  
   
   
       21 . A filter assembly, comprising: 
 an enclosure having at least one cavity;    at least one wall of the enclosure comprised of a circuit board; and    at least one tuning element, wherein the at least one tuning element extends into the at least one cavity of the enclosure.    
   
   
       22 . The filter assembly of  claim 21 , further comprising: 
 a trace formed on the circuit board; and    at least one circuit element, coupled to the trace.    
   
   
       23 . The filter assembly of  claim 21 , wherein the at least one tuning element is formed on the circuit board.  
   
   
       24 . The filter assembly of  claim 21 , wherein the at least one tuning element is formed in the enclosure.  
   
   
       25 . The filter assembly of  claim 21 , wherein the at least one tuning element is formed in a wall of the enclosure.  
   
   
       26 . A method of tuning a filter assembly, comprising: 
 forming a cavity body with at least one chamber with at least one opening in the cavity body;    covering the openings in the cavity body with structural elements to enclose the at least one chamber, wherein at least one structural element is a circuit board; and    tuning the electrical characteristics of the cavity body by selectively adjusting an element on the circuit board.    
   
   
       27 . The method of  claim 26 , further comprising: 
 forming a trace on the at least one circuit board; and    coupling at least one circuit element to the trace.    
   
   
       28 . The method of  claim 26 , wherein the element on the circuit board comprises a capacitor.  
   
   
       29 . The method of  claim 26 , wherein the element on the circuit board comprises an inductor.  
   
   
       30 . The method of  claim 26 , wherein the element on the circuit board comprises a mechanically adjustable tuning element, where the mechanically adjustable tuning element extends into the at least one chamber of the cavity body.  
   
   
       31 . A method of making a filter assembly, comprising: 
 forming a cavity body with at least one cavity and with at least one opening in the cavity body;    forming a trace on a printed circuit board;    coupling an electronic component to the trace; and    covering the at least one opening in the cavity body with the printed circuit board.    
   
   
       32 . The method of  claim 31 , wherein coupling the electronic component to the trace comprises coupling a low pass filter to the trace.  
   
   
       33 . The method of  claim 32 , wherein the low pass filter further comprises one of a circuit trace filter element and a mechanical structure filter element.  
   
   
       34 . The method of  claim 31 , wherein coupling the electronic component to the trace comprises coupling an amplifier circuit to the trace.  
   
   
       35 . The method of  claim 34 , wherein coupling the amplifier circuit comprises coupling at least one of a low noise amplifier and a power amplifier to the trace.  
   
   
       36 . The method of  claim 31 , wherein forming the circuit board further comprises forming a ground plane on a surface of the circuit board that forms a portion of the inner surface of the cavity body.  
   
   
       37 . The method of  claim 31 , wherein forming the circuit board further comprises forming multiple circuit trace layers.  
   
   
       38 . The method of  claim 31 , wherein forming the circuit board further comprises: 
 forming an input connector attached to the cavity body and coupled to the at least one cavity; and    forming an output connector attached to the cavity body and coupled to the at least one cavity.    
   
   
       39 . The method of  claim 31 , wherein forming the circuit board further comprises: 
 forming an input connector attached to the circuit board and coupled to the at least one cavity; and    forming an output connector attached to the circuit board and coupled to the at least one cavity.    
   
   
       40 . The method of  claim 31 , wherein forming the circuit board further comprises: 
 forming a first and a second low noise amplifier;    forming an input connector attached to the circuit board and coupled to an input of the first low noise amplifier;    forming an input coupling pad mounted in the at least one cavity and coupled to an output of the first low noise amplifier;    forming an output connector attached to the circuit board coupled to an output of the second low noise amplifier; and    forming an output coupling pad mounted in the at least one cavity and coupled to an input of the second low noise amplifier.    
   
   
       41 . The method of  claim 31 , wherein forming the circuit board further comprises forming an inter-stage coupling circuit, the inter-stage coupling circuit comprising: 
 at least one input coupling structure mounted in the at least one cavity; and    at least one output coupling structure mounted in the at least one cavity and coupled to the at least one input coupling structure.    
   
   
       42 . The method of  claim 41 , wherein forming the inter-stage coupling circuit further comprises forming a signal trace on the circuit board.  
   
   
       43 . The method of  claim 42 , wherein forming the signal trace further comprises one of forming the signal trace in an internal circuit layer of the circuit board and forming the signal trace in a surface circuit layer of the circuit board.  
   
   
       44 . A method of making a filter assembly, comprising: 
 forming a cavity body with at least one chamber with at least one opening in the cavity body;    covering the openings in the cavity body with structural elements to enclose the at least one chamber, wherein at least one structural element is a circuit board; and    forming at least one test circuit on the at least one circuit board.    
   
   
       45 . The method of  claim 44 , further comprising: 
 forming a trace on the at least one circuit board; and    coupling at least one circuit element to the trace.    
   
   
       46 . The method of  claim 44 , further comprising forming the test circuit with a connector.  
   
   
       47 . The method of  claim 44 , wherein forming the test circuit on the circuit board further comprises forming a signal tap.  
   
   
       48 . The method of  claim 44 , wherein forming the test circuit formed on the circuit board further comprises a forming a directional coupler, comprising: 
 forming a signal line; and    forming a sampling line, wherein the sampling line is run in parallel to the signal line and is physically proximate.    
   
   
       49 . The method of  claim 48 , further comprising forming the directional coupler with a terminating resistance.  
   
   
       50 . The method of  claim 48 , further comprising forming the directional coupler with a stub terminator.  
   
   
       51 . The method of  claim 48 , further comprising forming the sampling line on a same circuit layer as the signal line.  
   
   
       52 . The method of  claim 48 , further comprising forming the sampling line on a first circuit layer and forming the signal line on a second circuit layer.  
   
   
       53 . A microwave system, comprising: 
 an antenna;    a RF system; and    a filter assembly coupled to the antenna and to the RF system, wherein the filter assembly comprises: 
 an enclosure having at least one cavity;  
 at least one circuit board comprising a wall of the enclosure;  
 a trace formed on the at least one circuit board; and  
 at least one circuit element coupled to the trace.  
   
   
   
       54 . The microwave system of  claim 53 , wherein the circuit board further comprises a ground plane on a surface of the circuit board that forms a portion of the inner surface of the enclosure.  
   
   
       55 . The microwave system of  claim 53 , wherein the at least one circuit board further comprises multiple circuit trace layers.  
   
   
       56 . The microwave system of  claim 53 , wherein the at least one circuit element further comprises a low pass filter.  
   
   
       57 . The microwave system of  claim 56 , wherein the low pass filter further comprises one of a circuit trace filter element and a mechanical structure filter element.  
   
   
       58 . The microwave system of  claim 53 , wherein the at least one circuit element further comprises an amplifier.  
   
   
       59 . The microwave system of  claim 58 , wherein the amplifier is one of a low noise amplifier and a power amplifier.  
   
   
       60 . The microwave system of  claim 53 , wherein the filter assembly further comprises: 
 an input connector attached to the enclosure and coupled to the at least one cavity; and    an output connector attached to the enclosure and coupled to the at least one cavity.    
   
   
       61 . The microwave system of  claim 53 , wherein the filter assembly further comprises: 
 an input connector attached to the circuit board and coupled to the at least one cavity; and    an output connector attached to the circuit board and coupled to the at least one cavity.    
   
   
       62 . The microwave system of  claim 58 , wherein the filter assembly further comprises: 
 an input connector attached to the circuit board and coupled to the at least one cavity;    an output connector attached to the circuit board coupled to an output of the amplifier; and    an output coupling pad mounted in the at least one cavity and coupled to an input of the amplifier.    
   
   
       63 . The microwave system of  claim 58 , wherein the filter assembly further comprises: 
 an input connector attached to the circuit board and coupled to an input of the amplifier;    an input coupling pad mounted in the at least one cavity and coupled to an output of the amplifier; and    an output connector attached to the circuit board coupled to the at least one cavity.    
   
   
       64 . The microwave system of  claim 53 , wherein the filter assembly further comprises: 
 a first and a second low noise amplifier;    an input connector attached to the circuit board and coupled to an input of the first low noise amplifier;    an input coupling pad mounted in the at least one cavity and coupled to an output of the first low noise amplifier;    an output connector attached to the circuit board coupled to an output of the second low noise amplifier; and    an output coupling pad mounted in the at least one cavity and coupled to an input of the second low noise amplifier.    
   
   
       65 . The microwave system of  claim 53 , wherein the filter assembly further comprises: 
 a first filter stage and a second filter stage formed in the enclosure, wherein the first and second filter stage each have at least one cavity;    an input connector attached to the circuit board and coupled to the first filter stage;    an output coupling structure mounted in the at least one cavity of the first filter stage and coupled to an input of a low noise amplifier;    an input coupling structure mounted in the at least one cavity of the second filter stage and coupled to an output of the low noise amplifier; and    an output connector attached to the circuit board coupled to the at least one cavity of the second filter stage.    
   
   
       66 . The microwave system of  claim 53 , wherein the at least one circuit formed in the at least one circuit board comprises an inter-stage coupling circuit, the inter-stage coupling circuit comprising: 
 at least one input coupling structure mounted in the at least one cavity; and    at least one output coupling structure mounted in the at least one cavity and coupled to the at least one input coupling structure.