Surface acoustic wave filter and saw filter package

Abstract

A polar SAW (Surface Acoustic Wave) filter includes a band-pass ladder type SAW filter having a SAW resonator. A two-terminal pair circuit is serially connected to the band-pass ladder type SAW filter and includes a plurality of inductors. The polar SAW filter has attenuation poles in each of the higher-frequency and lower-frequency attenuation ranges of a pass band.

1. A polar SAW filter comprising:
 a first serial arm SAW resonator having a first and a second electrode connected to an input port and an output port, respectively; 
 a first parallel arm SAW resonator having a first electrode connected to the input port; 
 a second parallel arm SAW resonator having a first electrode connected to the output port; 
 a first inductor having a first terminal connected to a second electrode of said first parallel arm SAW resonator and a second terminal connected to a ground terminal; 
 a second inductor having a first terminal connected to a second electrode of said second parallel arm SAW resonator and a second terminal connected to the ground terminal; and 
 a third inductor having a first terminal directly connected to the second electrode of said first parallel arm SAW resonator and a second terminal directly connected to the second electrode of said second parallel arm SAW resonator. 
 
     
     
       2. The polar SAW filter in accordance with  claim 1 , further comprising:
 a second serial arm SAW resonator having a first and a second electrode connected to the input port and the first electrode of said first serial arm SAW resonator, respectively; 
 a third parallel arm SAW resonator having a first electrode connected to the input port; and 
 a fourth inductor having a first terminal connected to a second electrode of said third parallel arm SAW resonator and a second terminal connected to the ground terminal. 
 
     
     
       3. The polar SAW filter in accordance with  claim 2 , further comprising a supporting member in a form of package or chip on which said polar SAW filter is fabricated, said first, second, third and fourth inductors being in a form of electrical connection formed on said supporting member. 
     
     
       4. The polar SAW filter in accordance with  claim 3 , wherein said first, second and fourth inductors are in a form of bonding wire formed on said supporting member and connecting the second electrodes of said first, second and third parallel SAW resonators to the ground terminal. 
     
     
       5. The polar SAW filter in accordance with  claim 3 , wherein said third inductor is in a form of electrode pattern formed on said supporting member and connecting the second electrodes of said first and second parallel SAW resonators to each other. 
     
     
       6. The polar SAW filter in accordance with  claim 3 , wherein said first, second, fourth and third inductors are in a form of bonding wire formed on said supporting member and connecting the second electrodes of said first, second and third parallel SAW resonators to the ground terminal, and the second electrodes of said first and second parallel SAW resonators to each other, respectively. 
     
     
       7. The polar SAW filter in accordance with  claim 1 , further comprising a supporting member in a form of package or chip on which said polar SAW filter is fabricated, said first, second and third inductors being in a form of electrical connection formed on said supporting member. 
     
     
       8. The polar SAW filter in accordance with  claim 7 , wherein said first, second and third inductors are in a form of bonding wire formed on said supporting member and connecting the second electrodes of said first and second parallel SAW resonators to the ground terminal, and to each other, respectively. 
     
     
       9. The polar SAW filter in accordance with  claim 7 , wherein said first and second inductors are in a form of bonding wire formed on said supporting member and connecting the second electrodes of said first and second parallel SAW resonators to the ground terminal. 
     
     
       10. The polar SAW filter in accordance with  claim 7 , wherein said third inductor is in a form of electrode pattern formed on said supporting member and connecting the second electrodes of said first and second parallel SAW resonators to each other. 
     
     
       11. A polar SAW filter comprising:
 a first serial arm SAW resonator having a first electrode and a second electrode connected to an input port and an output port, respectively;   a first parallel arm SAW resonator having a first electrode connected to the input port;   a second parallel arm SAW resonator having a first electrode connected to the output port;   a first inductor having a first terminal connected to a second electrode of said first parallel arm SAW resonator and having a second terminal connected to a ground terminal;   a second inductor having a first terminal connected to a second electrode of said second parallel arm SAW resonator and having a second terminal connected to the ground terminal;   a third inductor having a first terminal connected to the second electrode of said first parallel arm SAW resonator and having a second terminal connected to the second electrode of said second parallel arm SAW resonator; and   a supporting member in a form of a package or a chip on which said polar SAW filter is fabricated, said first, second and third inductors being in a form of electrical connection formed on said supporting member,   said first and second inductors being in a form of a bonding wire formed on said supporting member and connecting the second electrodes of said first and second parallel SAW resonators to the ground terminal.   
     
     
       12. The polar SAW filter in accordance with  claim 11 , further comprising:
 a second serial arm SAW resonator having a first electrode and a second electrode connected to the input port and the first electrode of said first serial arm SAW resonator, respectively;   a third parallel arm SAW resonator having a first electrode connected to the input port; and   a fourth inductor having a first terminal connected to a second electrode of said third parallel arm SAW resonator and having a second terminal connected to the ground terminal.   
     
     
       13. The polar SAW filter in accordance with  claim 12 , wherein said fourth inductor is in a form of an electrical connection formed on said supporting member. 
     
     
       14. The polar SAW filter in accordance with claim  13  15, wherein said fourth inductor is in a form of a bonding wire formed on said supporting member and connecting the second electrode of said third parallel SAW resonator to the ground terminal. 
     
     
       15. The A polar SAW filter in accordance with  claim 13  comprising:
 a first serial arm SAW resonator having a first electrode and a second electrode connected to an input port and an output port, respectively; 
 a first parallel arm SAW resonator having a first electrode connected to the input port; 
 a second parallel arm SAW resonator having a first electrode connected to the output port; 
 a first inductor having a first terminal connected to a second electrode of said first parallel arm SAW resonator and having a second terminal connected to a ground terminal; 
 a second inductor having a first terminal connected to a second electrode of said second parallel arm SAW resonator and having a second terminal connected to the ground terminal; 
 a third inductor having a first terminal connected to the second electrode of said first parallel arm SAW resonator and having a second terminal connected to the second electrode of said second parallel arm SAW resonator; and 
 a supporting member in a form of a package or a chip on which said polar SAW filter is fabricated, said first, second and third inductors being in a form of electrical connection formed on said supporting member; 
 a second serial arm SAW resonator having a first electrode and a second electrode connected to the input port and the first electrode of said first serial arm SAW resonator, respectively; 
 a third parallel arm SAW resonator having a first electrode connected to the input port; and 
 a fourth inductor having a first terminal connected to a second electrode of said third parallel arm SAW resonator and having a second terminal connected to the ground terminal, 
 said first and second inductors being in a form of a bonding wire formed on said supporting member and connecting the second electrodes of said first and second parallel SAW resonators to the ground terminal, 
 wherein said third inductor is in a form of an electrode pattern formed on said supporting member and connecting the second electrodes of said first and second parallel SAW resonators to each other, and 
 wherein said fourth inductor is in a form of an electrical connection formed on said supporting member. 
 
     
     
       16. The polar SAW filter in accordance with  claim 13 , wherein said fourth and third inductors are in a form of a bonding wire formed on said supporting member and connecting the second electrode of said third parallel SAW resonator to the ground terminal, and the second electrodes of said first and second parallel SAW resonators to each other, respectively. 
     
     
       17. The polar SAW filter in accordance with  claim 11 , wherein said third inductor is in a form of a bonding wire formed on said supporting member and connecting the second electrodes of said first and second parallel SAW resonators to each other. 
     
     
       18. The polar SAW filter in accordance with  claim 11 , wherein said third inductor is in a form of an electrode pattern formed on said supporting member and connecting the second electrodes of said first and second parallel SAW resonators to each other. 
     
     
       19. A polar SAW filter formed on a piezoelectric substrate and having an input port and an output port, the input port receiving an input signal and the output port outputting an output signal, comprising:
 a first serial arm SAW resonator having a first electrode and a second electrode, the first electrode receiving a signal relative to the input signal, the second electrode transmitting a signal relative to the output signal;   a first parallel arm SAW resonator having a third electrode connected to the first electrode and having a fourth electrode;   a second parallel arm SAW resonator having a fifth electrode connected to the second electrode and having a sixth electrode;   a first contact pad formed on the piezoelectric substrate and connected to the fourth electrode;   a second contact pad formed on the piezoelectric substrate and connected to the sixth electrode;   a first inductor connected between the first contact pad and a ground potential;   a second inductor connected between the second contact pad and the ground potential; and   a third inductor formed on the piezoelectric substrate and connected directly to both the first and second contact pads.   
     
     
       20. The polar SAW filter in accordance with claim  19  21, further comprising:
 a second serial arm SAW resonator connected between the input port and the first electrode; 
 a third parallel arm SAW resonator having a seventh electrode connected to the input port and having an eighth electrode; and 
 a fourth inductor connected between the eighth electrode and the ground potential. 
 
     
     
       21. The A polar SAW filter in accordance with  claim 19  formed on a piezoelectric substrate and having an input port and an output port, the input port receiving an input signal and the output port outputting an output signal, comprising:
 a first serial arm SAW resonator having a first electrode and a second electrode, the first electrode receiving a signal relative to the input signal, the second electrode transmitting a signal relative to the output signal; 
 a first parallel arm SAW resonator having a third electrode connected to the first electrode and having a fourth electrode; 
 a second parallel arm SAW resonator having a fifth electrode connected to the second electrode and having a sixth electrode; 
 a first contact pad formed on the piezoelectric substrate and connected to the fourth electrode; 
 a second contact pad formed on the piezoelectric substrate and connected to the sixth electrode; 
 a first inductor connected between the first contact pad and a ground potential; 
 a second inductor connected between the second contact pad and the ground potential; and 
 a third inductor formed on the piezoelectric substrate and connected directly to both the first and second contact pads, 
 wherein the third inductor is formed by a bonding wire. 
 
     
     
       22. The polar SAW filter in accordance with  claim 21 , wherein each of the first and second inductors are formed by a bonding wire. 
     
     
       23. The polar SAW filter in accordance with  claim 22 , further comprising a package on which the piezoelectric substrate is mounted. 
     
     
       24. The polar SAW filter in accordance with  claim 23 , further comprising a third contact pad formed on the package, wherein the first inductor is connected between the first contact pad and the third contact pad, and the second inductor is connected between the second contact pad and the third contact pad. 
     
     
       25. The polar SAW filter in accordance with  claim 19 , wherein the third inductor is formed by an interconnecting pattern. 
     
     
       26. The polar SAW filter in accordance with  claim 25 , wherein each of the first and second inductors are formed by a bonding wire. 
     
     
       27. The polar SAW filter in accordance with  claim 26 , further comprising a package on which the piezoelectric substrate is mounted. 
     
     
       28. The polar SAW filter in accordance with  claim 27 , further comprising a third contact pad formed on the package, wherein the first inductor is connected between the first contact pad and the third contact pad, and the second inductor is connected between the second contact pad and the third contact pad. 
     
     
       29. A surface acoustic wave filter comprising:
 a first SAW resonator located between a first node and a second node;   a second SAW resonator located between the first node and a third node;   a third SAW resonator located between the second node and a fourth node;   a first bonding wire directly connected between the third and fourth nodes;   a second bonding wire connected between the fourth node and a ground node; and   a piezoelectric substrate on which the first, second and third SAW resonators, the third node and the fourth node are located.   
     
     
       30. The surface acoustic wave filter of claim 29, wherein the second bonding wire is directly connected between the fourth node and the ground node. 
     
     
       31. The surface acoustic wave filter of claim 29, further comprising a third bonding wire connected between the third node and ground. 
     
     
       32. The surface acoustic wave filter of claim 29, wherein the first node is electrically connected to an input terminal, and the second node is electrically connected to an output terminal. 
     
     
       33. The surface acoustic wave filter of claim 32, further comprising a fourth SAW resonator located between the input terminal and the first node. 
     
     
       34. The surface acoustic wave filter of claim 33, further comprising a fifth SAW resonator located between the input terminal and ground. 
     
     
       35. The surface acoustic wave filter of claim 29, wherein the second SAW resonator is directly connected to the third node, and the third SAW resonator is directly connected to the fourth node. 
     
     
       36. The surface acoustic wave filter of claim 35, wherein the third and fourth nodes are contact pads. 
     
     
       37. A surface acoustic wave filter comprising:
 a first SAW resonator electrically connected to a first node and a second node;   a second SAW resonator electrically connected to the first node and a third node;   a third SAW resonator electrically connected to the second node and a fourth node;   a first bonding wire directly connected between the third and fourth nodes;   a second bonding wire connected between the fourth node and a ground node; and   a piezoelectric substrate on which the first, second and third SAW resonators, the third node and the fourth node are located.   
     
     
       38. The surface acoustic wave filter of claim 37, wherein the second bonding wire is directly connected between the fourth node and the ground node. 
     
     
       39. The surface acoustic wave filter of claim 37, further comprising a third bonding wire connected between the third node and ground. 
     
     
       40. The surface acoustic wave filter of claim 37, wherein the first node is electrically connected to an input terminal, and the second node is electrically connected to an output terminal. 
     
     
       41. The surface acoustic wave filter of claim 40, further comprising a fourth SAW resonator located between the input terminal and the first node. 
     
     
       42. The surface acoustic wave filter of claim 41, further comprising a fifth SAW resonator located between the input terminal and ground. 
     
     
       43. The surface acoustic wave filter of claim 37, wherein the second SAW resonator is directly connected to the third node, and the third SAW resonator is directly connected to the fourth node. 
     
     
       44. The surface acoustic wave filter of claim 43, wherein the third and fourth nodes are contact pads. 
     
     
       45. A surface acoustic wave filter comprising:
 a serial arm SAW resonator having a first side and a second side;   a first contact pad;   a second contact pad;   a first parallel arm SAW resonator connected to the first side of the serial arm SAW resonator and the first contact pad;   a second parallel arm SAW resonator connected to the second side of the serial arm SAW resonator and the second contact pad;   a first bonding wire directly connected between the first and second contact pads; and   a second bonding wire directly connected with both of the second contact pad and a ground pad,   wherein the first parallel arm SAW resonator is directly connected to the first contact pad, and the second parallel arm SAW resonator is directly connected to the second contact pad.   
     
     
       46. A surface acoustic wave filter comprising:
 a serial arm SAW resonator having a first side and a second side;   a first contact pad;   a second contact pad;   a first parallel arm SAW resonator connected to the first side of the serial arm SAW resonator and the first contact pad;   a second parallel arm SAW resonator connected to the second side of the serial arm SAW resonator and the second contact pad;   a first bonding wire directly connected between the first and second contact pads;   a second bonding wire directly connected with both of the second contact pad and a ground pad; and   a piezoelectric substrate with the first and second contact pads, the serial arm SAW resonator and the first and second parallel arm SAW resonators thereon.   
     
     
       47. The surface acoustic wave filter of claim 46, further comprising a third bonding wire directly connected with both of the first contact pad and the ground pad. 
     
     
       48. A SAW filter package comprising:
 a package body;   a piezoelectric substrate formed on the package body;   a first SAW resonator formed on the piezoelectric substrate, wherein the first SAW resonator is electrically connected between a first node and a second node;   a second SAW resonator formed on the piezoelectric substrate, wherein the second SAW resonator is electrically connected between the first node and a third node, the third node being located on the piezoelectric substrate;   a third SAW resonator formed on the piezoelectric substrate, wherein the third SAW resonator is electrically connected between the second node and a fourth node, the fourth node being located on the piezoelectric substrate;   a first bonding wire directly connected between the third and fourth nodes;   a ground pad formed on the package body; and   a second bonding wire connected between the fourth node and the ground pad.   
     
     
       49. The SAW filter package of claim 48, wherein the second bonding wire is connected directly with both of the fourth node and the ground pad. 
     
     
       50. The SAW filter package of claim 49, wherein the third SAW resonator is connected directly with both of the second node and the fourth node. 
     
     
       51. The SAW filter package of claim 48, further comprising a third bonding wire connected between the third node and ground. 
     
     
       52. The SAW filter package of claim 48, wherein the first node is electrically connected to a first contact pad formed on the package body, and the second node is electrically connected to a second contact pad formed on the package body which is different from the first contact pad. 
     
     
       53. The SAW filter package of claim 52, further comprising a fourth SAW resonator formed on the piezoelectric substrate, wherein the fourth SAW resonator is electrically connected between the first contact pad and ground. 
     
     
       54. The SAW filter package of claim 48, wherein the second SAW resonator is directly connected to the third node, and the third SAW resonator is directly connected to the fourth node. 
     
     
       55. The SAW filter package of claim 54, wherein the third and fourth nodes are contact pads.